Disable GlobalMediaControlsCastStartStop in MR integration tests

The tests haven't been fully updated to support the feature and are
broken on the private waterfall bots. The feature will be re-enabled
once the tests have been updated.

Bug: 1233190, 1229305, b/194820305
Change-Id: I1fed6426b74cbbdaccd8247e743807fae058d767
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3057645


Reviewed-by: Muyao Xu <muyaoxu@google.com>
Commit-Queue: Takumi Fujimoto <takumif@chromium.org>
Cr-Commit-Position: refs/heads/master@{#906344}