Add for fix audio track null point

These is a timing issue that clear track will later than create
  if disconnect phone A and connect phone B at the same time
If the disconnection flow will not end,
  DUT will not allow speaker B to be connected

Bug: 287563400
Test: atest net_test_btif_stack

Change-Id: I5b673e792bf9cbcedd62b590436328f2c4a68ed9