GitLab

- Remove the webui lock screen tests.
- Re-enable flaky test since it should no longer flake because there is
  no longer webui involved.

Bug: 899777
Change-Id: I759ad6d20a08ad48e6a992fcfca9a25572ad16a5
Reviewed-on: https://chromium-review.googlesource.com/c/1327163
Commit-Queue: Jacob Dufault <jdufault@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609819}