Attach launcher protection scrim to the opening target instead of

Launcher's surface.

Bug: 317183323
Flag: NONE
Test: m -j
Test: Swipe back to home, make sure there's no flicker. Try both quick
swipes and slow swipes. Try staying in apps for different durations and
then swipe back.

Change-Id: I59df680d889489291b28610ff76693a63e55e49a