A2DP Offload: Don't crash on repeated endSession

AudioOffload endSession is called from multiple places.
Do not crash if session has already ended.

Also, added/enabled extra log messages to help debug similar issues.

Bug: 80148693
Test: Manual
Change-Id: I409c0146f9629cee6bdabf16e52e88201ee02267
Merged-In: I409c0146f9629cee6bdabf16e52e88201ee02267
(cherry picked from commit 7a2110d6660b080b0242fc385cce3c9748c49090)