GTTF: Send 1% of Chromium try jobs to recipe-based builders.

BUG=317931
R=cmp@chromium.org, joi@chromium.org

Review URL: https://codereview.chromium.org/108243005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243288 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243288