AudioManager: restore getVolumeGroupIdForAttributes behavior

Allow getVolumeGroupIdForAttributes() to fallback
to default volume group as it was before commiti c8e375e0.

Bug: 267588552
Test: atest AudioServiceHostTest#testAudioVolumeGroups
Change-Id: I571ffd8c1b51bbce943bfac4cd4f628e282fcc12
1 file changed