As referenced in the OpenStack documentation, the firewall_driver in
nova.conf should be set to nova.virt.firewall.NoopFirewallDriver, "so
that nova-compute does not perform iptables-based filtering itself".
Without this change, the driver gets set to
nova.virt.libvirt.firewall.IptablesFirewallDriver, which seems to
make networking unusable.
Change-Id: Id9cce0f5f4efe719683aaf3284b128188b61b919
Closes-bug: #1246888