Reset PIP position when canceling swipe up

onStop() is a confirmed signal of user leaving Launcher. In most use
cases, we use onUserLeaveHint() to move PIP. However, in some cases,
onUserLeaveHint() does not get triggered. It's still a good signal for
those use cases because it happens sooner than onStop() and is not
interrupted by focus change. In order to address cases that
onUserLeaveHint() is not triggered (e.g. cancelling swipe up), onStop()
pushes PIP to the right position. In other cases, we simply set it
twice, which does not hurt.

Change-Id: Ia206590d10d673b16196bbab927a24aaae3ba46b
Fixes: 77648293
Test: manual test