No PiP position update when unlock

KeyguardService#wrap attempts to call TransitionUtil#createLeash for all
existing Tasks and reset them to (0, 0), which would cause flicker when
unlock with PiP being present.

Flag: EXEMPT bugfix
Bug: 416299223
Video: http://recall/-/aaaaaabFQoRHlzixHdtY/fvJW62TYq575AS2SDcBYuA
Test: Repeatedly lock and unlock with PiP being represent, see Video
Change-Id: Id03554324ef50a94ac9767076f8668d6c7e1f0cf