[stable-only] Load config options importing common_config

In newer versions (Zed+), [1] enforces to explicitly load the
configuration options by calling ``register_common_config_options``
method. In older releases, those options are loaded when the
module ``common_config`` is loaded.

[1]https://review.opendev.org/c/openstack/neutron/+/837392

Related-Bug: #1979072
Change-Id: Iad4ac8cb00a11d2f6646966d37e6f9b160f8ecf4

Author: ralonsoh

neutron/cmd/remove_duplicated_port_bindings.py

@@ -20,15 +20,14 @@
 from oslo_db import options as db_options
 from oslo_log import log as logging
 
-from neutron.common import config as common_config
+from neutron.common import config as common_config  # noqa
 from neutron.objects import ports as ports_obj
 
 
 LOG = logging.getLogger(__name__)
 
 
 def setup_conf(conf):
-    common_config.register_common_config_options()
     db_group, neutron_db_opts = db_options.list_opts()[0]
     conf.register_cli_opts(neutron_db_opts, db_group)
     conf()