MediaProjection: stop media projection activity result from being stored after being sent

Ensure that activity results force sent for media projection are only scheduled to be sent once, and not stored to be re-sent on when resuming. Also update the documentation for MediaProjection#createVirtualDisplay to properly document a previously known outcome of a SecurityException being thrown.

Bug: 271577674
Fix: 271577674
Test: atest WmTests:ActivityRecordTests
Change-Id: Ie43290a1ddbd9dedfe9217d7c19c1d5b890d4331