Prevent timeout of async rotation by invisible windows

This avoids a delay to re-show the bars when an async window
is removed during rotation (e.g. volume panel) since shell
transition disables the usages of setOrientationChanging.

This is also a step to be able to completely remove
get/setOrientationChanging in the future.

Also simplify prepareSurfaceLocked:
 - showRobustly always returns true, so the corresponding
   "else" can be removed.
 - isParentWindowHidden is already checked in isOnScreen.

Bug: 270123439
Test: TransitionTests#testDisplayRotationChange
Change-Id: I53bae0d937d63e4b600aed3a005a3f8c7d5b68b5