a2dp: stop instead of disconnecting on offload fail

Instead of disconnecting AVDTP when offload fails trigger stop stream.
The offload may be failing due to ongoing SCO.

Bug: 340245529
Bug: 345709100
Flag: com.android.bluetooth.flags.stop_on_offload_fail
Test: mmm packages/modules/Bluetooth
Change-Id: I10bde20ee93efad30a472c99912262f22cb85634