Fix presubmit after my latest changes

This is a follow-up to https://codereview.chromium.org/179453003/

Removing CheckRietveldTryJobExecution because the implementation
is currently empty anyway and the trybot config will become more and more
dynamic so that static list is becoming less and less accurate.

BUG=317931
R=maruel@chromium.org

Review URL: https://codereview.chromium.org/183623002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253896 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253896