[PIP] Remove PIP when recovering from systemui crash

PIP can end up in a broken state if systemui crashes. To fix this we
implement a callback in onTaskAppeared, which gets triggered on crash
recovery, and clean up pip if so.

Bug: 376048041
Test: manual, crash systemui and verify no pip
Flag: EXEMPT bugfix
Change-Id: I6311c7d20a784b822122fd5373609b25436d0b61