Use AnimatorTestRule to test animations

The tests are flaky since the "dispatch to main thread operation" takes unexpected time to complete. This will lead to the situation: A is expected to start before B finishes, but A eventually executes after B finishes.
We use AnimatorTestRule to test the result of the frame after a specific time of animation.

Bug: 303132156
Test: atest SystemUITests:WindowMagnificationAnimationControllerTest
Change-Id: I76cca141b2b892ec832b3cf0e0ce106533feebf4