Bump internal webrtc iOS bots to iOS 12.0

And remove custom expiration_time for release bots because currently
it equals to default value

Bug: webrtc:10047
Change-Id: Ife7fd154237575e3d43f7be814e1156624166dab
Reviewed-on: https://webrtc-review.googlesource.com/c/120604
Commit-Queue: Artem Titarenko <artit@webrtc.org>
Reviewed-by: Oleh Prypin <oprypin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26471}
diff --git a/tools_webrtc/ios/internal.client.webrtc/iOS64_Debug.json b/tools_webrtc/ios/internal.client.webrtc/iOS64_Debug.json
index 2af3a44..cbb1a5e 100644
--- a/tools_webrtc/ios/internal.client.webrtc/iOS64_Debug.json
+++ b/tools_webrtc/ios/internal.client.webrtc/iOS64_Debug.json
@@ -20,7 +20,7 @@
     {
       "include": "real_device_tests.json",
       "device type": "iPhone 6s",
-      "os": "11.4.1",
+      "os": "12.0",
       "pool": "chrome.tests"
     }
   ]
diff --git a/tools_webrtc/ios/internal.client.webrtc/iOS64_Release.json b/tools_webrtc/ios/internal.client.webrtc/iOS64_Release.json
index 922fa97..e7f260d 100644
--- a/tools_webrtc/ios/internal.client.webrtc/iOS64_Release.json
+++ b/tools_webrtc/ios/internal.client.webrtc/iOS64_Release.json
@@ -24,6 +24,5 @@
       "os": "11.4.1",
       "pool": "chrome.tests"
     }
-  ],
-  "expiration_time": 3600
+  ]
 }
diff --git a/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_dbg.json b/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_dbg.json
index 50eef7c..cbb1a5e 100644
--- a/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_dbg.json
+++ b/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_dbg.json
@@ -20,7 +20,7 @@
     {
       "include": "real_device_tests.json",
       "device type": "iPhone 6s",
-      "os": "10.3.3",
+      "os": "12.0",
       "pool": "chrome.tests"
     }
   ]
diff --git a/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_rel.json b/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_rel.json
index 58d4063..e7f260d 100644
--- a/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_rel.json
+++ b/tools_webrtc/ios/internal.tryserver.webrtc/ios_arm64_rel.json
@@ -21,9 +21,8 @@
     {
       "include": "real_device_tests.json",
       "device type": "iPhone 6s",
-      "os": "10.3.3",
+      "os": "11.4.1",
       "pool": "chrome.tests"
     }
-  ],
-  "expiration_time": 3600
+  ]
 }