Revert of Fix PRESUBMIT.py after disabling CQ. (patchset #1 id:1 of https://codereview.webrtc.org/1192673003/)

Reason for revert:
CQ-Rietveld combination now supports webrtc custom domain.

Original issue's description:
> Fix PRESUBMIT.py after disabling CQ.
>
> The disabling of CQ in https://codereview.webrtc.org/1177243003/
> broke PRESUBMIT.py since it's trying to read cq.cfg.
>
> BUG=501332
> TBR=phoglund@webrtc.org
>
> Committed: https://chromium.googlesource.com/external/webrtc/+/141725f50fa4223ce2f9e84500971a44d7720c03

TBR=phoglund@webrtc.org,kjellander@webrtc.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=501332

Review URL: https://codereview.webrtc.org/1190283003

Cr-Commit-Position: refs/heads/master@{#9476}
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 6925c7e..c429009 100755
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -338,7 +338,7 @@
 # pylint: disable=W0613
 def GetPreferredTryMasters(project, change):
   cq_config_path = os.path.join(
-      change.RepositoryRoot(), 'infra', 'config', 'cq_disabled.cfg')
+      change.RepositoryRoot(), 'infra', 'config', 'cq.cfg')
   # commit_queue.py below is a script in depot_tools directory, which has a
   # 'builders' command to retrieve a list of CQ builders from the CQ config.
   is_win = platform.system() == 'Windows'