Clear the A2DP active device within the native stack during cleanup

Use explicit SetActivePeer(RawAddress::kEmpty) for BtifAvSource and
BtifAvSink during Cleanup()

Also, replaced incorrectly classified BTIF_TRACE_WARNING() log messages
with LOG_INFO().

Bug: 73832547
Test: Manual - A2DP streaming, enable Location -> Bluetooth scanning,
      restart Bluetooth in Quick Settings
Change-Id: Ieeae8915a45dc0c98cd68bd4bb113424c2de74d9