cc: Remove GetPreferredTryMasters from cc/PRESUBMIT.py.

GetPreferredTryMasters overrides the set of default trybots for
'git cl try' but we only want to run the linux_blink_rel trybot in the
CQ.

BUG=581850
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel

Review URL: https://codereview.chromium.org/1646693003

Cr-Commit-Position: refs/heads/master@{#372273}
1 file changed