ClearAllRecents: force recents activity to finish when idle
When another app is launched from navbar ring or quick settings (or
whatever other way), recents activity will end up in a paused state
which prevents recents key from working correctly next time it's
pressed. We force finish of recents activity in case it was not resumed
in specified amount of time (500ms).
This also fixes stuck clear all navbar key - it will go away when finish
runnable is fired