Lock free app animations (7/n): Cleanup

- Make sure persister pausing is working
- Make sure Surface animation thread is being boosted
- Move all remaining fields from AppWindowAnimator and NUKE it,
also remove getAnimLayerAdjustment and do the z-boosting
directly on the AppWindowToken.

Bug: 64674361
Test: go/wm-smoke
Test: Inspect thread priorities before/during/after animations
Change-Id: Ie64c8231bcebd8536eab476ee9f2c51abf85480c