Remove nova-network deprecated options

The following WARN logs always appears in nova-api.log:
- Option "firewall_driver" from group "DEFAULT" is deprecated for removal.
- Option "linuxnet_interface_driver" from group "DEFAULT" is deprecated
for removal.

These 2 options can be removed for the following reasons:
- nova-network will be deprecated
- moreover Kolla doesn't configure nova-network

Options deprecation notes is here:
https://github.com/openstack/nova/blob/master/releasenotes/notes/deprecate-more-nova-network-opts-a9f87c79f7d26438.yaml#L8
https://github.com/openstack/nova/blob/master/releasenotes/notes/deprecate-more-nova-network-opts-a9f87c79f7d26438.yaml#L37

Change-Id: I12f80a02b9d27f2bdbb8926eb648ea4f6e6dd945

ansible/roles/nova/templates/nova.conf.j2

@@ -18,14 +18,6 @@ metadata_workers = {{ openstack_service_workers }}
 metadata_listen = {{ api_interface_address }}
 metadata_listen_port = {{ nova_metadata_port }}
 
-firewall_driver = nova.virt.firewall.NoopFirewallDriver
-
-{% if neutron_plugin_agent == "openvswitch" %}
-linuxnet_interface_driver = nova.network.linux_net.LinuxOVSInterfaceDriver
-{% elif neutron_plugin_agent == "linuxbridge" %}
-linuxnet_interface_driver = nova.network.linux_net.NeutronLinuxBridgeInterfaceDriver
-{% endif %}
-
 allow_resize_to_same_host = true
 
 {% if enable_ironic | bool %}