merge_pr_49814

FLEDGE: Make B&A WPT tests more hermetic

...by making sure to always explicitly use a .test coordinator.

Bug: 383600441
Change-Id: Ib163b5042ebfdb04d906c9bd549f323cbed45768
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6094505
Reviewed-by: Mason Freed masonf@chromium.org
Reviewed-by: Russ Hamilton behamilton@google.com
Commit-Queue: Maks Orlovich morlovich@chromium.org
Cr-Commit-Position: refs/heads/main@{#1399474}