When accessibility services are running, in particular touch
exploration, the default stream override delay in AudioService
makes it hard for the user to change the notification volume
as when TalkBack speaks, the user would control the media
volume during the utterance, and up until 5s after its end.
Use a shorter delay when touch exploration is enabled.
Bug 17140435
Change-Id: Iabadb9778f2957b5aa0aebd1599f2d69bd83222b
873cc45da2