Provide a quick workaround for WM flaky tests

Some ActivityRecord would leak after cts because of isAnimating.
Which might caused from the starting window was transferred to the
other activity after apply reveal animation on server side.

Test: atest AmStartOptionsTests#testDashW_FinishingTop, then check
there is no WindowState leak after test finish.
Bug: 184830058

Change-Id: Id7a09ab141367f0e0788155c13d658f251b8fa1b