Wait for SurfaceAnimationThread before teardown

Dispose the SurfaceAnimationThread before tearing down the mocks in test do
avoid NPE due to mocks being teared down when the SurfaceAnimationRunner
callback are triggered.

Bug: b/144270260
Test: atest WmTests:DisplayContentTests
Change-Id: Iead191ab046379967210ca92db270e897ff43b68
2 files changed