Run peerconnection_unittests on multiple shards.

The shards were removed with https://webrtc-review.googlesource.com/c/src/+/261262 as an experiment.

It turns out the new test target slow_peer_connection_unittests doesn't take much time compared to peerconnection_unittests.
slow_peer_connection_unittests: 7min
peerconnection_unittests: 35min
https://chromium-swarm.appspot.com/tasklist?f=parent_task_id-tag%3A5aad344b2285be11&st=1651756987488

Bug: webrtc:14025
Change-Id: Iaaf2b476ea6fdc419c5b14beb8040c5a0d973952
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/261264
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Jeremy Leconte <jleconte@google.com>
Cr-Commit-Position: refs/heads/main@{#36785}
diff --git a/infra/specs/client.webrtc.json b/infra/specs/client.webrtc.json
index 9d8f620..627e2a0 100644
--- a/infra/specs/client.webrtc.json
+++ b/infra/specs/client.webrtc.json
@@ -270,7 +270,8 @@
               "device_type": "bullhead",
               "os": "Android"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test": "peerconnection_unittests",
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
@@ -900,7 +901,8 @@
               "device_type": "bullhead",
               "os": "Android"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test": "peerconnection_unittests",
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
@@ -1288,7 +1290,8 @@
               "device_type": "bullhead",
               "os": "Android"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test": "peerconnection_unittests",
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
@@ -1567,7 +1570,8 @@
               "device_type": "bullhead",
               "os": "Android"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test": "peerconnection_unittests",
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
@@ -2197,7 +2201,8 @@
               "device_type": "bullhead",
               "os": "Android"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test": "peerconnection_unittests",
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
@@ -2579,7 +2584,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       }
@@ -2756,7 +2762,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -3166,7 +3173,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -3576,7 +3584,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -3986,7 +3995,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -4396,7 +4406,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -4806,7 +4817,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -5217,7 +5229,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -5629,7 +5642,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -6040,7 +6054,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -6482,7 +6497,8 @@
               "cpu": "x86-64",
               "os": "Mac-11"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -6912,7 +6928,8 @@
               "cpu": "x86-64",
               "os": "Mac-11"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -7333,7 +7350,8 @@
               "cpu": "x86-64",
               "os": "Mac-11"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -7773,7 +7791,8 @@
               "os": "Mac",
               "pool": "WebRTC-baremetal"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -8042,7 +8061,8 @@
               "cpu": "x86-64",
               "os": "Windows-7-SP1"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       }
@@ -8221,7 +8241,8 @@
               "cpu": "x86-64",
               "os": "Windows-7-SP1"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -8653,7 +8674,8 @@
               "cpu": "x86-64",
               "os": "Windows-10-15063"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
diff --git a/infra/specs/test_suites.pyl b/infra/specs/test_suites.pyl
index e0a3f6d..92de58d 100644
--- a/infra/specs/test_suites.pyl
+++ b/infra/specs/test_suites.pyl
@@ -44,7 +44,11 @@
           'shards': 6
         },
       },
-      'peerconnection_unittests': {},
+      'peerconnection_unittests': {
+        'swarming': {
+          'shards': 4
+        },
+      },
       'rtc_media_unittests': {},
       'rtc_pc_unittests': {},
       'rtc_stats_unittests': {},
@@ -101,7 +105,11 @@
           'shards': 6
         },
       },
-      'peerconnection_unittests': {},
+      'peerconnection_unittests': {
+        'swarming': {
+          'shards': 4
+        },
+      },
       'rtc_media_unittests': {},
       'rtc_pc_unittests': {},
       'rtc_stats_unittests': {},
@@ -223,7 +231,11 @@
       }
     },
     'more_configs_tests': {
-      'peerconnection_unittests': {},
+      'peerconnection_unittests': {
+        'swarming': {
+          'shards': 4
+        },
+      },
     },
     'win_video_capture_tests': {
       'video_capture_tests': {
diff --git a/infra/specs/tryserver.webrtc.json b/infra/specs/tryserver.webrtc.json
index 9c98e37..0d5500c 100644
--- a/infra/specs/tryserver.webrtc.json
+++ b/infra/specs/tryserver.webrtc.json
@@ -270,7 +270,8 @@
               "device_type": "bullhead",
               "os": "Android"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test": "peerconnection_unittests",
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
@@ -934,7 +935,8 @@
               "device_type": "bullhead",
               "os": "Android"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test": "peerconnection_unittests",
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
@@ -1598,7 +1600,8 @@
               "device_type": "bullhead",
               "os": "Android"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test": "peerconnection_unittests",
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
@@ -2020,7 +2023,8 @@
               "device_type": "bullhead",
               "os": "Android"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test": "peerconnection_unittests",
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
@@ -2296,7 +2300,8 @@
               "device_type": "bullhead",
               "os": "Android"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test": "peerconnection_unittests",
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
@@ -5893,7 +5898,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -6309,7 +6315,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -6720,7 +6727,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -6978,7 +6986,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       }
@@ -7155,7 +7164,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -7565,7 +7575,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -8025,7 +8036,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -8435,7 +8447,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -8845,7 +8858,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -9255,7 +9269,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -9665,7 +9680,8 @@
               "cpu": "x86-64",
               "os": "Ubuntu-18.04"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -10083,7 +10099,8 @@
               "cpu": "x86-64",
               "os": "Mac-11"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -10514,7 +10531,8 @@
               "cpu": "x86-64",
               "os": "Mac-11"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -10943,7 +10961,8 @@
               "os": "Mac",
               "pool": "WebRTC-baremetal-try"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -11364,7 +11383,8 @@
               "cpu": "x86-64",
               "os": "Mac-11"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -11832,7 +11852,8 @@
               "os": "Mac",
               "pool": "WebRTC-baremetal-try"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -12253,7 +12274,8 @@
               "cpu": "x86-64",
               "os": "Windows-10-15063"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -12667,7 +12689,8 @@
               "cpu": "x86-64",
               "os": "Windows-7-SP1"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -13077,7 +13100,8 @@
               "cpu": "x86-64",
               "os": "Windows-10-15063"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -13487,7 +13511,8 @@
               "cpu": "x86-64",
               "os": "Windows-7-SP1"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -13897,7 +13922,8 @@
               "cpu": "x86-64",
               "os": "Windows-7-SP1"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -14307,7 +14333,8 @@
               "cpu": "x86-64",
               "os": "Windows-7-SP1"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       },
@@ -14615,7 +14642,8 @@
               "cpu": "x86-64",
               "os": "Windows-7-SP1"
             }
-          ]
+          ],
+          "shards": 4
         },
         "test_id_prefix": "ninja://pc:peerconnection_unittests/"
       }