Lock free app animations (6/n): Move back-pressure to new animator

SurfaceFlinger was currently only back-pressuring the old
animation system. Move this to the new SurfaceAnimationRunner,
such that every animation frame is presented on screen.

Test: go/wm-smoke
Test: Insert 16ms sleep statement when applying transaction, make
sure animations are still smooth.
Bug:

Change-Id: I510d22c9c4359659e7a061a26b7adad9c265b734