Fix bug where quickly ending folder animation with back swipe caused icons not clipped to folder

1. Fix a race condition that the new animation is reading stale UI state which should have been reset in previous animation.
2. Don't set clipChildren=true on folder page view during open folder animation

Fix: 282158620
Test: open folder and quickly back swipe, verify app icons are still clipped
Change-Id: I5f0877fe4157533563df922ba50a6ad540c9ba6e