Remove sync_integration_tests_run from chromium_swarm_tests.

All tests listed in chromium_swarm_tests are going to be run on the CI
infrastructure. Sadly, sync_integration_tests_run is currently failing on all
OSes, so commenting it out in the meantime until we focus on adding back more
tests.

R=csharp@chromium.org
BUG=157234
NOTRY=true

Review URL: https://codereview.chromium.org/170283007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252057 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252057