Tighten up pending animations list.

- When we can't start an animation for a task, preemptively remove the
  task from the animation list so that it does not erroneously report as
  animating, or inherit the affect-sysui-flags behaviour.

Bug: 77223419
Test: atest FrameworksServicesTests:com.android.server.wm.RecentsAnimationControllerTest
Change-Id: I5cbc9e68d182cecacf10932a3220039dda5ebeed