[OVN] OVN agent should register the correct config options

[Rodolfo Alonso]

Commit [1] reduced the number of loaded config options when the OVN agent is started. However this patch removed the load of the core common options, as seen in the puppet CI [2]:
"""

Jun 29 23:45:47 np0003949382.novalocal neutron-ovn-agent[95988]: sys.exit(main())
Jun 29 23:45:47 np0003949382.novalocal neutron-ovn-agent[95988]: File "/usr/lib/python3.9/site-packages/neutron/cmd/eventlet/agents/ovn_neutron_agent.py", line 26, in main
Jun 29 23:45:47 np0003949382.novalocal neutron-ovn-agent[95988]: ovn_neutron_agent.main()
Jun 29 23:45:47 np0003949382.novalocal neutron-ovn-agent[95988]: File "/usr/lib/python3.9/site-packages/neutron/agent/ovn/ovn_neutron_agent.py", line 37, in main
Jun 29 23:45:47 np0003949382.novalocal neutron-ovn-agent[95988]: config.init(sys.argv[1:])
Jun 29 23:45:47 np0003949382.novalocal neutron-ovn-agent[95988]: File "/usr/lib/python3.9/site-packages/neutron/common/config.py", line 105, in init
Jun 29 23:45:47 np0003949382.novalocal neutron-ovn-agent[95988]: msg = validators.validate_regex(cfg.CONF.base_mac, validators.MAC_PATTERN)
Jun 29 23:45:47 np0003949382.novalocal neutron-ovn-agent[95988]: File "/usr/lib/python3.9/site-packages/oslo_config/cfg.py", line 2223, in __getattr__
Jun 29 23:45:47 np0003949382.novalocal neutron-ovn-agent[95988]: raise NoSuchOptError(name)
Jun 29 23:45:47 np0003949382.novalocal neutron-ovn-agent[95988]: oslo_config.cfg.NoSuchOptError: no such option base_mac in group [DEFAULT]

"""

[1]https://review.opendev.org/c/openstack/neutron/+/878565
[2]https://logserver.rdoproject.org/openstack-periodic-daily/review.rdoproject.org/rdoinfo/master/weirdo-bobcat-promote-puppet-scenario005-centos-stream-9/9f93f3b/logs/weirdo-project/logs/systemctl.txt.gz

[Brian Haley (brian-haley)]

https://review.opendev.org/c/openstack/neutron/+/887363

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/neutron 23.0.0.0b3 development milestone.