While AVDT opened or its AVRC_TIMER_EVT expired, it is no needed to start the 2nd AVDT stream

There were 2 cases to start the 2nd stream automatically by the stack:

* When the 2nd AVDT opened, the stack would check the 1st stream state
  to determinate the 2nd should be starting or not.
* While the AVRC timer which was fired after AVDT opened was expired,
  the stack would open the AVRC and start the 2nd stream if the 1st was
  started.

Both of them are unnecessary since all the stream must be controlled by
the upper layer. We currently support an active device only, and the
2nd stream will be tracked as remote triggered and suspended immediately.
To samplize the behavior, it is better to not start the 2nd stream
automatically by the stack.

Bug: 132146974
Bug: 150797902
Test: manual
Change-Id: I75f39801e9779ee55fa574e30051e01966c61ea3
Merged-In: I75f39801e9779ee55fa574e30051e01966c61ea3
(cherry picked from commit ff12fc04)