Revert "rpc: Fix slow volume download (virsh vol-download)"
    
    This reverts commit d9c9e138f22c48626f719f880920e04c639e0177.
    
    Unfortunately, things are going to be handled differently so this
    commit must go.
    
    Signed-off-by: Michal Privoznik <mprivozn@redhat.com>