neutron meter agent can not find netns

[Xi Wenhao]

In the stable/2024.1 version, I attempted to use the Neutron meter functionality for network traffic statistics. However, the Neutron meter agent was unable to create the related iptables entries. After troubleshooting and debugging, I discovered that the /var/run/netns directory was not shared in the container, causing the check for the existence of netns to return false. Here is my solution:

Add a line in the kolla-ansible/ansible/role/neutron/default/main.yaml:
neutron_metering_agent_default_volumes:
  - "/var/run/netns:/var/run/netns:shared"