vc: Improve handlig Reset Flag

After reconnection of the remote device, which has persist flag set to 0x00
(reset volume), Android shall always try to set its own volume. Either
already groupVolume (which is there if one of the set member is
connected or group was previously connected), or volume taken from audio
framework.

Without this patch, if during streaming to first bud, second bud would
connect with reset volume != 0, the reset volume was applied to both
buds which is no expected behavior.

Bug: 365858502
Test: atest VolumeControlServiceTest
Test: manual on UPF
Flag: Exempt, regression tested with unit tests
Change-Id: I126aa05fa252ab280e04f2dc718604217a1e18fe