AdapterService: Remove LE Audio active device before activating A2DP

For some  controllers the A2DP Offloader HCI command needs to be called
when the ISO Data Path is removed. Therefore make sure to close LeAudio
stream before making A2DP device active

Bug: 307481636
Test: manual switch between A2DP and LE Audio headset while streaming
Tag: #feature
Change-Id: I41420220f42131eac31b8ec44b369ef4f7ced5f1