Disable more SyncerThreadTests on the "Mac (tsan)" bot.

This change disables three more SyncerThreadTests that exceeded timeouts on the "Mac (tsan)" bot when I logged into the bot and manually ran the test.

TBR=timurrrr,glider,thestig
BUG=85892
TEST=make the "Chromium Mac (tsan)" bot greener.
Review URL: http://codereview.chromium.org/7145017

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@88947 0039d316-1c4b-4281-b951-d872f2087c98