libvirtd default network should be disabled on CLC

[nephomaniac]

libvirtd default network should be disabled on CLC, and prevent dnsmasq to be started. dnsmasq will disallow eucanetd to be restarted. dnsmasq is particularly bad for MANAGED modes if CC is co-located with CLC (dnsmasq will prevent dhcpd to be started). Currently one needs to monitor a QL and kill dnsmasq in MANAGED mode in order to run tests.