Ensure that fold overlay is removed after playing animation

The fold animation overlay stayed on the screen
even after animation has played or if playing
was cancelled midway.

Bug: 327965719
Test: quickly fold/unfold the device
  => check that overlay is removed
Test: fold => check that overlay is removed
  after several seconds

Change-Id: I3dc2590ff46e93cfaa912a047fa5892878f9922e