[Sheriff] Temporarily mark array-literal-feedback as flaky for GC stress.

The test is blocking the v8 lkgr. It will be unmarked again after there is infrastructure to disable it on GC stress only.

BUG=
TBR=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/143463004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18700 ce2b1a6d-e550-0410-aec6-3dcde31c8c00