AudioService: do not unmute when ringer mode affects stream

Do not allow a volume command to affect the mute mode when the ringer
or zen mode is affecting the mute state of that stream.

Flag: EXEMPT bugfix
Test: atest VolumeHelperTest
Bug: 391178691
Change-Id: Ief7b2d6840aa9506435db5c1abc96a32ca50e994