Make fling thresholds consistent

There are 3 places we can block a fling:
- Swiping from home to all apps (through overview)
- Swiping from an app to all apps (through overview)
- Dismissing a task (in the same gesture that started by swiping down)

In all of these cases, we block the fling when crossing the threshold
to a new state (e.g. OVERVIEW), but unblock if the user pauses their
drag. With this change, the logic is consistent:
- Unblock the fling after pausing a short amount of time
- If a fling was blocked, increase the settling duration based on
  velocity

Bug: 78089840
Bug: 78658678
Change-Id: I5ef52b74229418b867b26c3c6d3db2cf6e48914b