ExternalGatewayForFloatingIPNotFound: External network is not reachable from subnet Therefore, cannot associate Port with a Floating IP

[chandan kumar]

periodic-tripleo-ci-centos-9-standalone-tempest-wallaby job is failing at following tempest test,
```
tempest.api.volume.test_volumes_actions.VolumesActionsTest.test_attach_detach_volume_to_instance[compute,id-fff42874-7db5-4487-a8e1-ddda5fb5288d,smoke]
-------------------------------------------------------------------------------------------------------------------------------------------------------

Captured traceback:
~~~~~~~~~~~~~~~~~~~
    Traceback (most recent call last):
      File "/usr/lib/python3.9/site-packages/tempest/common/utils/__init__.py", line 70, in wrapper
        return f(*func_args, **func_kwargs)
      File "/usr/lib/python3.9/site-packages/tempest/api/volume/test_volumes_actions.py", line 45, in test_attach_detach_volume_to_instance
        server = self.create_server()
      File "/usr/lib/python3.9/site-packages/tempest/api/volume/base.py", line 230, in create_server
        body, _ = compute.create_test_server(
      File "/usr/lib/python3.9/site-packages/tempest/common/compute.py", line 353, in create_test_server
        LOG.exception('Server %s failed to delete in time',
      File "/usr/lib/python3.9/site-packages/oslo_utils/excutils.py", line 227, in __exit__
        self.force_reraise()
      File "/usr/lib/python3.9/site-packages/oslo_utils/excutils.py", line 200, in force_reraise
        raise self.value
      File "/usr/lib/python3.9/site-packages/tempest/common/compute.py", line 324, in create_test_server
        _setup_validation_fip(
      File "/usr/lib/python3.9/site-packages/tempest/common/compute.py", line 101, in _setup_validation_fip
        clients.floating_ips_client.update_floatingip(
      File "/usr/lib/python3.9/site-packages/tempest/lib/services/network/floating_ips_client.py", line 41, in update_floatingip
        return self.update_resource(uri, post_data)
      File "/usr/lib/python3.9/site-packages/tempest/lib/services/network/base.py", line 77, in update_resource
        resp, body = self.put(req_uri, req_post_data)
      File "/usr/lib/python3.9/site-packages/tempest/lib/common/rest_client.py", line 363, in put
        return self.request('PUT', url, extra_headers, headers, body, chunked)
      File "/usr/lib/python3.9/site-packages/tempest/lib/common/rest_client.py", line 703, in request
        self._error_checker(resp, resp_body)
      File "/usr/lib/python3.9/site-packages/tempest/lib/common/rest_client.py", line 809, in _error_checker
        raise exceptions.NotFound(resp_body, resp=resp)
    tempest.lib.exceptions.NotFound: Object not found
    Details: {'type': 'ExternalGatewayForFloatingIPNotFound', 'message': 'External network 84bf1927-4067-46da-a289-1636bd1f2f64 is not reachable from subnet 99c55e30-7435-47fb-9be9-a26cd46b2fcf. Therefore, cannot associate Port 8faba232-4e36-4cb7-8353-4af1edccb327 with a Floating IP.', 'detail': ''}

```
Same tempest rpm openstack-tempest-31.0.0-0.20220608165917.abddb57.el9.noarch(exists in both component ci testing and current-tripleo) is used in passing and failing job.

The job started failing from https://review.rdoproject.org/zuul/builds?job_name=periodic-tripleo-ci-centos-9-standalone-tempest-wallaby&skip=0 2022-06-13 18:08:38

It is a tracker bug, will add more information as we investigate.

Links:
[failing job]. https://logserver.rdoproject.org/54/36254/116/check/periodic-tripleo-ci-centos-9-standalone-tempest-wallaby/d073cbf/logs/undercloud/var/log/tempest/tempest_run.log.txt.gz

[Passing job] https://logserver.rdoproject.org/openstack-component-tempest/opendev.org/openstack/tripleo-ci/master/periodic-tripleo-ci-centos-9-standalone-tempest-wallaby/31fe87c/logs/undercloud/var/log/tempest/tempest_run.log.txt.gz

[chandan kumar (chkumar246)]

By looking at neutron logs and compairing with passing job,

https://logserver.rdoproject.org/54/36254/116/check/periodic-tripleo-ci-centos-9-standalone-tempest-wallaby/d073cbf/logs/undercloud/var/log/containers/neutron/server.log.txt.gz

```
if_exists=True) do_commit /usr/lib/python3.9/site-packages/ovsdbapp/backend/ovs_idl/transaction.py:90
2022-06-14 02:24:28.930 15 ERROR ovsdbapp.backend.ovs_idl.transaction [req-3f5cec56-4039-4520-b6ec-d993b56fe469 9a0073051e7c4a6aae3ed9eb107c44bf e803f82a18c742eba606e656a2fc1e54 - default default] Traceback (most recent call last):
  File "/usr/lib/python3.9/site-packages/ovsdbapp/backend/ovs_idl/connection.py", line 131, in run
    txn.results.put(txn.do_commit())
  File "/usr/lib/python3.9/site-packages/ovsdbapp/backend/ovs_idl/transaction.py", line 93, in do_commit
    command.run_idl(txn)
  File "/usr/lib/python3.9/site-packages/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/commands.py", line 763, in run_idl
    raise ovn_exc.RevisionConflict(
neutron.common.ovn.exceptions.RevisionConflict: OVN revision number for b30bc58e-35c1-497c-9482-52ad32b0dc19 (type: ports) is equal or higher than the given resource. Skipping update
```

Not sure above error is linked with the failure.

[chandan kumar (chkumar246)]

https://review.rdoproject.org/r/c/rdoinfo/+/43460/1//COMMIT_MSG
```
Uping tempest-31.0.0 to test with wait_until_sshable_pingable patches

https://review.opendev.org/q/topic:wait_until_sshable_pingable

Depends-On: https://review.rdoproject.org/r/c/openstack/tempest-distgit/+/43404
Depends-On: https://review.rdoproject.org/r/c/rdo-jobs/+/40247
Depends-On: https://review.opendev.org/c/openstack/openstack-tempest-skiplist/+/842095
```
Similar tests are failing here during backport patches.

https://logserver.rdoproject.org/60/43460/1/check/distgit-tripleo-ci-centos-9-standalone-full-tempest-api-wallaby/2b6e034/logs/undercloud/var/log/tempest/tempest_run.log.txt.gz

[chandan kumar (chkumar246)]

The job https://review.rdoproject.org/zuul/builds?job_name=periodic-tripleo-ci-centos-9-standalone-tempest-wallaby&skip=0 is back to green after merging https://review.rdoproject.org/r/c/openstack/tempest-distgit/+/43369