Apply touch velocity to screenshot UI on dismissal ACTION_UP

Previously ACTION_UP would initiate the dismissal animation, but would
not update the location the the UI based upon the time elapsed since the
last ACTION_MOVE last caused an update to the UI location.

Bug: 413411582
Test: Manual swipe test across small/large screens, observing smoother
      transition from touch to animation.
Flag: EXEMPT narrow bugfix
Change-Id: I1338ddd7d92ef61d38357d6babe30ea990109c38