Uninitialized currentTrackInfo cause assertion in onLiveEdgeSearchCompleted at availabilityStartTime

Created by: davemevans

onLiveEdgeSearchCompleted was called before the currentTrackInfo is valid, since this is only valid once the segment list has been generated.

The fix is to ensure that the DATE_UPDATE_COMPLETED handler for the schedule controller is called before that of the stream (by subscribing them in the correct order). This ensures that the current track info is valid before the live edge search is started and there is something for the live edge search completed handler to reference.

Additionally, scheduling is no longer started in the live edge search complete handler but in the stream updated handler, as (I think) was intended when that handler was added.