Don't play or cancel window animations of controllable insets sources

All the animations should be controlled by the client. This CL also
removes the redundant logic about selecting the window animation for the
system bar.

Fix: 255273300
Test: Rotate screen while playing a video in Photos in immersive mode.
      See if system bars stay invisible as expected.
Change-Id: I9b2bb73ce898b4753aef8dae6685f67d935d0648