Fix gcl try after PRESUBMIT files have been modified for multiple tryserver support
Fix gcl try after PRESUBMIT files have been modified for multiple tryserver support

Note that other waterfalls are not guaranteed to support triggering via HTTP
or SVN. That's why this hardcodes tryserver.chromium.

BUG=334892

Review URL: https://codereview.chromium.org/197553009

git-svn-id: bd64dd6fa6f3f0ed0c0666d1018379882b742947@256947 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

svn2github/chromium-depot-tools,svn2github/chromium-depot-tools,svn2github/chromium-depot-tools