Enable neutron plugin for Octavia

This patch cleary enables a `neutron plugin` for the functional test
of `tacker-functional-devstack-multinode-sol-kubernetes` in zuul.

[1] is fixed in the Octavia on the assumption that using a `octavia
create_network_interface_device` function[2] of the Neutron.
According to [1], if using the Octavia, it seems that the
`neutron plugin` needs to be clearly define.

Also currentry the functional test of
`tacker-functional-devstack-multinode-sol-kubernetes` is not became
`-1` status on zuul when zuul's result even is `RETRY_LIMIT` because
 job's voting is `non-vorting`. So this patch changes from
`non-voting` to `voting` in zuul's job results.

[1] 651f095a81
[2] https://github.com/openstack/neutron/blob/master/devstack/lib/octavia#L7-L28

Closes-Bug: 1919396
Change-Id: I999a2c7c06528c7470cec2161bdd361a67a8da6f

.zuul.yaml

@@ -305,6 +305,7 @@
           barbican: https://opendev.org/openstack/barbican
           heat: https://opendev.org/openstack/heat
           mistral: https://opendev.org/openstack/mistral
+          neutron: https://opendev.org/openstack/neutron
           octavia: https://opendev.org/openstack/octavia
         devstack_services:
           base: false
@@ -451,7 +452,6 @@
       - ^doc/.*$
       - ^releasenotes/.*$
       - ^contrib/.*$
-    voting: false
 
 - project:
     templates:

devstack/local.conf.kubernetes

@@ -35,7 +35,8 @@ Q_AGENT=openvswitch
 Q_USE_SECGROUP=False
 LIBVIRT_FIREWALL_DRIVER=nova.virt.firewall.NoopFirewallDriver
 
-# Enable heat, networking-sfc, barbican and mistral
+# Enable neutron, heat, networking-sfc, barbican and mistral
+enable_plugin neutron https://opendev.org/openstack/neutron master
 enable_plugin heat https://opendev.org/openstack/heat master
 enable_plugin networking-sfc https://opendev.org/openstack/networking-sfc master
 enable_plugin barbican https://opendev.org/openstack/barbican master