koji_builder: don't restart the old monolythic libvirtd
    
    In Fedora libvirt switched to a collection of socket activated services
    instead of a large single libvirtd service. Restarting that service
    caused the socket activated ones to die and then libvirtd exited on
    idle, leaving nothing handling virt connections.
    
    So, lets stop trying to restart that and no need to notify other things
    because they should idle out/restart on socket activation.
    
    Signed-off-by: Kevin Fenzi <kevin@scrye.com>