Shell-Transition: call maybeFinishStylusHandwriting when swiping on navBar

Since the laucher is no longer rely on RecentsAnimationController to signal
the recent task being gestured out to home with shell-transition and it
replaced with WindowManagerService#setRecentsAppBehindSystemBars.

So that maybeFinishStylusHandwriting missed to call with enabling
shell-transition

Add the missed call in WindowManagerService#setRecentsAppBehindSystemBars
to fix this issue.

Fix: 253259123
Test: atest StylusHandwritingTest#\
       testStylusSession_fingerTriggersNavbarGestures passed on the
      device with enabling shell-transition
Change-Id: I958d013c0511dccb0a0d751b811c0fff1bfb8a04