AudioService: Use proper stream context for Le Audio stream volume

When volume level is restored after mode change from incoming call back
to normal mode (media playback) invalid contextual stream was used to
calculate volume level. Should use getBluetoothContextualVolumeStream()
instead.
Additonally, the workaround for some cases where we don't get the proper
LE Audio device was moved into the 'setLeAudioVolumeOnModeUpdate()'.

Bug: 241501978
Tag: #feature
Test: verified manually, missed and placed call scenario, check restored volume value
Change-Id: Ibc1b92c8ea053ccab3cf4c66afce6e6e9c5c9e53