Exclude flaky tests from presubmit.

There are two separate FlakyTest annotations. Only one of them was
initially excluded from presubmit runs, so tests annotated with the
second were still being run. Adding the second annotation to the list of
exclusions so that none of the flaky tests run during presubmit.

Bug: 150503078
Test: Navigate to directory and run `atest`
Change-Id: Id85a2181654bb4039e4ae0a13269cf1a160e43c0