Force finish pending frame drawn callback once launcher is stopped

- In rare cases, we may schedule to update the taskview with a
  screenshot but Launcher will not finish calling back because
  the activity is stopped (can be the result of the animation
  cancelling back to the app), which prevents Launcher from
  scheduling any frames and properly decrementing the frame
  count.

Bug: 202776119
Test: Launch an app with sharesheet, swipe up and verify that
      screenshot callbacks
Change-Id: I6b7e121fd5d9ef27ef5cccca060a4ff819fe9acc