Wait enough time for WMS#waitForAnimationsToComplete

As CL[1] added more log for tracking animating container in
waitForAnimationsToComplete, which accidentally ignored waiting
enough time when WindowAnimator#isAnimationScheduled has set but not
yet having animating container, in case syncInputTransactions going too
earily and tests might flaky when verifying input events should be
touched but WindowAnimator is still animate, we should wait enough
time when the animation scheduling to WindowAnimator.

[1]: I2c0370d6abe0f726891cedd39b6f8fa9fd366e94

Bug: 188904558
Test: atest -bidt WindowUntrustedTouchTest --iteration 50

Change-Id: I3b009e23e7a43d0f450e7f4aef4d13c0f4e04547