virt.define_vol_xml_str variant using an existing libvirt connection
virt.define_vol_xml_str variant using an existing libvirt connection

In order to avoid connection multiple times when reusing this function
in the virt module, create _define_vol_xml_str not caring about the
connection opening and closing.

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