leaudio: Try to configure group as soon as possible

When doing group switch, Bluetooth already knows what is the Audio HAL
configuration for the Audio Session and could configure the stream
already when GroupSetActive is called

Bug: 331775328
Flag: Exempt, regression tested with unit tests
Test: atest bluetooth_le_audio_client_test

Change-Id: I677524f2bc130b3beeb9cb3aa7361b14629ec506