Respect letterbox config for exiting pip with fixed orientation

1. If the display ignores orientation request, no need to send
   the target rotation to PipTaskOrganizer. Otherwise the animation
   for PiP-to-fullscreen will have a rotation effect.
2. Because requested orientation is ignored, the activity with
   fixed orientation will be letterboxed. Then when expanding pip,
   it should resolve letterbox policy configuration. Otherwise
   there will be additional non-letterbox config change that causes
   to flicker.

Fix: 235599028
Test: DiplayContentTests#testFixedRotationWithPip
Change-Id: Icc94238d349e19627e6d9316f7525b9e531c71b5