The test may spawn threads that reference the global clock, so the
code that resets the fake clock, needs to run when those threads
have been stopped.
Bug: webrtc:13947
Change-Id: I1f7dc921b7a8ff8e7e89e03e4397e635b67d77be
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/258361
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36489}