No responce from metadata server when reusing port

[Vasyl Saienko]

The metadata server returns 404 when using the same port for new instance in
less than cache_timeout.

Steps to reproduce:
1. Enable metadata caching
2. Run test neutron_tempest_plugin.scenario.test_ports.PortsTest.test_previously_used_port
3. The test will fail with

Traceback (most recent call last):

  File "/var/lib/openstack/lib/python3.6/site-packages/tempest/lib/common/ssh.py", line 107, in _get_ssh_connection

    sock=proxy_chan)

  File "/var/lib/openstack/lib/python3.6/site-packages/paramiko/client.py", line 446, in connect

    passphrase,

  File "/var/lib/openstack/lib/python3.6/site-packages/paramiko/client.py", line 764, in _auth

    raise saved_exception

  File "/var/lib/openstack/lib/python3.6/site-packages/paramiko/client.py", line 664, in _auth

    self._transport.auth_publickey(username, pkey)

  File "/var/lib/openstack/lib/python3.6/site-packages/paramiko/transport.py", line 1580, in auth_publickey

    return self.auth_handler.wait_for_response(my_event)

  File "/var/lib/openstack/lib/python3.6/site-packages/paramiko/auth_handler.py", line 250, in wait_for_response

    raise e

paramiko.ssh_exception.AuthenticationException: Authentication failed.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):

  File "/var/lib/openstack/lib/python3.6/site-packages/neutron_tempest_plugin/scenario/test_ports.py", line 74, in test_previously_used_port

    self.keypair['private_key'])

  File "/var/lib/openstack/lib/python3.6/site-packages/neutron_tempest_plugin/scenario/base.py", line 217, in check_connectivity

    ssh_client.test_connection_auth()

  File "/var/lib/openstack/lib/python3.6/site-packages/neutron_tempest_plugin/common/ssh.py", line 153, in connect

    *args, **kwargs)

  File "/var/lib/openstack/lib/python3.6/site-packages/tempest/lib/common/ssh.py", line 121, in _get_ssh_connection

    password=self.password)

tempest.lib.exceptions.SSHTimeout: Connection to the 10.11.12.196 via SSH timed out.

User: cirros, Password: None

[Vasyl Saienko (vsaienko)]

I think the issue was fixed on neutron side by: https://review.opendev.org/#/q/If6a5866e4406c9c6c30e989c79ffb4ee1a88cecf