Prevent early onEnterAnimationComplete callback for recents target

- When starting the recents animation, we immediately change the visibility
  of home, which triggers the onEnterAnimationComplete for the target
  activity to be called.  We would like to use the callback on the client
  side to actually do work once the enter animation completes (in both
  the recents and non-recents animation case), so instead of sending the
  callback immediately, defer it until after the animation has actually
  completed.

Bug: 77730018
Test: Manual, tap home and ensure the client only gets
      onEnterAnimationComplete after the transition ends

Change-Id: I3f4b189712e61867d9185e32bda4afcc9d7e2849