Fix and promote WindowInsetsAnimImeTest

Fix testAnimationCallbacks_overlapping_opposite and promote it to
non-flaky test.

This was fixed by:
1. Waiting for all animations to finish before checking events.
2. IME animation events shouldn't be verified in-order with system bars.
   Use individual in-order events.
3. Correct the IME visibility for animation steps.

Fix: 159177559
Test: WindowInsetsAnimImeTest#testAnimationCallbacks_overlapping_opposite
Change-Id: Ie28a6b4eb1023a5d3c8a333373cece118455de14
1 file changed