[PiP2] Update magnetized target on config change

We need to make sure dismiss and magnetized target
are properly updated on configuration changes.
Otherwise, any display changes for instance lead to
incorrect magnetized target location.

Bug: 380336325
Flag: com.android.wm.shell.enable_pip2
Test: enter PiP w/ fixed-rotation and drag-to-dismiss
Test: enter PiP, fold/unfold, then drag-to-dismiss
Change-Id: I8cfe243d82392425fb8b3b2e6da20bd3d8f111cd