Don't notify animation finished if no animation

This removes commit ab9fcb21 to avoid potential recursion of
surface placement: onAnimationFinished -> onExitAnimationDone
-> destroySurfaces -> postWindowRemoveCleanupLocked
-> performSurfacePlacementNoTrace.

The original case no longer occurs without the invocation. And now
the window with mRemoveOnExit=true will be removed by WindowState #handleCompleteDeferredRemoval. And if there is only mAnimatingExit,
it will be handled by WS#cleanupAnimatingExitWindow.

The test testStuckExitingWindow is also removed because no matter
with calling onAnimationFinished or not in postApplyAnimation,
the test always passes.

Verified the original issue case: change language and swipe up.
There is no leftover EXITING window. Even hardcode to set the exit
flags unexpectedly, there is still no problem.

Bug: 237481770
Test: WindowStateTests#testDeferredRemovalByAnimating
      WindowContainerTests#testHandleCompleteDeferredRemoval

Change-Id: If10cd3c334476e078fdd4d4db05bf8b37db84ccc