Disable experimental tryserver builders.

They may be putting too much load on the tryserver.

TBR=joi

BUG=317931, 334681

Review URL: https://codereview.chromium.org/140503002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245063 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 245063