Fix the round corner and crop issue after auto-enter-pip

When auto-enter-pip from a Task with multiple activities, the leash of
the task will be animated before the top activity being reparented to
the pinned root task, we perform the cleanup on original task in
Task#clearLastRecentsAnimationTransaction.

What's fixed in this CL
- reset also the corner radius
- reset the window crop to be null

Test cases, auto-enter-pip by navigating to test Activity in ApiDemos
- from portrait, w/ source rect hint
- from portrait, w/o source rect hint
- from landscape, w/ source rect hint
- from landscape, w/o source rect hint

after entering PiP, exit to original task > hit back again and verify
that both corner radius and window crop are fine

Video: http://recall/-/aaaaaabFQoRHlzixHdtY/b8kkFJNjqw1Kj6yj8vfy36
Bug: 192564925
Test: manual, see description and video
Change-Id: I5363e310ec53c9ec1531e7b0aaf08ba488f55d96