[Sync::USS] Enabling Password integration test for USS

This CL enables Password browser tests for full blown USS
implementation.

Due to limitations in the test infrastructure, it's not possible to
run the integration tests against both pseudo and full-blown USS.
Therefore, this CL disables running passwords integration test against
the pseudo USS implementation.

Bug: 902349
Change-Id: If1da33e4e12b4b41a5ac97cd929d014ed5a17baf
Reviewed-on: https://chromium-review.googlesource.com/c/1439901
Commit-Queue: Mohamed Amir Yosef <mamir@chromium.org>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#627400}
7 files changed