[MediaProjection] Address deadlock between multiple services

Below outlines acceptable lock ordering:
* WindowManagerService -> MediaProjectionManagerService
* ActivityManagerService -> WindowManagerService

This change addresses deadlock caused by
MediaProjectionManagerService -> ActivityManagerService by
ensuring that MPMS -> AMS is never done while holding the
MPMS lock.

Bug: 291826358
Test: Manual & asking partner to validate monkey test
Change-Id: I63037ea099699ac9dba87086ea8caf0082e0c721