virt.volume_infos: silence libvirt error message
virt.volume_infos: silence libvirt error message

Even though the volume_infos handles the libvirt exception when a volume
is missing, libvirt was still outputting the error message in the log.
Since this can add noise to the log only record the libvirt error
message in debug level.

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt