Disable flaky TwoClient(Passwords|CustomPassphrase)SyncTest.SetPassphraseAndThenSetupSync on OS_CHROMEOS

R=treib@chromium.org

Bug: 956012
Change-Id: I138bc34165986d185a530e11accd0f60a22b5559
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1582040
Reviewed-by: Marc Treib <treib@chromium.org>
Auto-Submit: Gabriel Charette <gab@chromium.org>
Commit-Queue: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653566}
2 files changed