Pinned stack animation: Prevent window preservation during animation.

When moving to the fullscreen stack, we were triggering the
resized while not drag resizing logic, causing a window preservation
in the middle of the animation.

Bug: 35396882
Test: Move skeleton pinned app between states. Verify no freezes or size jumps during animation.
Change-Id: I4a72945742241b3a039b997a8da6aba89e935346