Fix logic for categorizing a volume group as invalid

A volume group is invalid if it contains as legacy stream only bt sco.
In Auto a volume group can contain multiple streams. See telring which
has ring, voice call and bt sco as legacy streams.

When a volume group contains only bt sco as legacy stream we try to
replace the mapping of bt_sco with voice_call if available.

Do not throw IAE when querrying the state of an inexistant volume group

Test: manual
Flag: com.android.media.audio.replace_stream_bt_sco
Bug: 354945865
Change-Id: Id1dcaec524dc141c8494f644257387d753e2239b