Fix a couple issues with swiping up from home

- Don't update the animation to go from 0 to 1; instead, update the
  interpolator to clamp to the remaining progress (b/79773309)
- Fix NPE that can happen in a race between the atomic animation
  ending and the non-atomic animation canceling/ending

Change-Id: I313251dc5cbd7b931b043fc3e840bb4ab368a790