Add escalation instructions to git cl upload

Bug: 1117305
Change-Id: I3233b1ddcbf50ac97a888e08f692193d4d83b3e9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/2641044Reviewed-by: Edward Lesmes <ehmaldonado@chromium.org>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>
Auto-Submit: Josip Sokcevic <sokcevic@google.com>

git_cl.py

@@ -2180,6 +2180,8 @@ class Changelist(object):
       raise GitPushError(
           'Failed to create a change. Please examine output above for the '
           'reason of the failure.\n'
+          'For emergencies, Googlers can escalate to '
+          'go/gob-support or go/notify#gob\n'
           'Hint: run command below to diagnose common Git/Gerrit '
           'credential problems:\n'
           '  git cl creds-check\n'