DNS resolution not working in rocky, queens

[DevX]

When trying to enabling Networking service internal/external DNS resolution it does not work and results in a broken cloud. Looking at the documentation for rocky/queens it looks like the name has change and was not updated accordingly.

https://docs.openstack.org/neutron/rocky/admin/config-dns-int.html

New name is `dns_domain_ports` and not `dns` as is listed in osa.

https://github.com/openstack/openstack-ansible-os_neutron/blob/stable/rocky/templates/plugins/ml2/ml2_conf.ini.j2#L8

The following changes were added user_variables.yml
```
neutron_designate_enabled: True
neutron_dns_domain: "example.org."

neutron_plugin_base:
  - router
  - metering
  - dns
```

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/599701

[OpenStack Infra (hudson-openstack)]

Change abandoned by Victor Palma (<email address hidden>) on branch: master
Review: https://review.openstack.org/599701
Reason: According to documentation DNS is still available if needed I can provide another patch that add dns domain ports.

[Georgina Shippey (gshippey)]

Fix released and backported to Rocky.
https://review.opendev.org/#/c/624097/