Comment 1 for bug 1912450

Port c25976f2-aea4-4b78-9a8f-e4ec2b1373e3 was not found on the integration bridge and will therefore not be processed

this log shows that when we update this port, the device qvoc25976f2-ae has been deleted, self.int_br.get_vifs_by_ids func will not found it, and it will be treated as 'skipped_devices'

from the defination of `treat_devices_skipped` func(https://opendev.org/openstack/neutron/src/tag/17.0.0/neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py#L2030-L2039), we can see, it doesn't delete any flows, this is the root cause of this problem.

as a comparison, treat_devices_removed func will delete flows when executing self.port_unbound method.