Update display orientation if rotated app is not in transition

It may happen when a translucent activity no longer affects display
orientation, e.g. enter pip, and the next fullscreen opaque activity
in the same task also declares fixed orientation.

Because the next activity is already visible, there won't be a
transition includes it, i.e. DC.FixedRotationTransitionListener#
onAppTransitionFinishedLocked won't be called to update orientation.
So handle the case when the previous transition is done, then the
display can follow the orientation request of the current top activity.

Fix: 384402546
Flag: EXEMPT bugfix
Test: DisplayContentTests#testRespectNonTopVisibleFixedOrientation
Change-Id: I4fce2f84254875d0b52252d428000d39f994f14b