Snapshot all tasks in pending recents animation when rotating devices

Since both of splitting tasks in split screen go to overview together
now, update to snapshot all pending animations when rotating while
showing overview to ensure both of splitting task snapshots are taken
with proper bounds before rotation.

Bug: 200813008
Test: atest RecentsAnimationControllerTest
Test: enter overview after activated split screen, observed task
      thumbnails showing with correct bounds after roation.
Change-Id: Id1101bf8be67593f85a43c1d4afae769ffc737d3