Upgrading or deploying overcloud fails due to "Name or service not known"

Issue

• Overcloud deploy or upgrade failed with Name or service not known message.
  In the following example, it failed to access https://overcloud.example.com:13000 due to the error.

  $ openstack overcloud upgrade run --stack overcloud --limit overcloud-controller-0
      :
  2023-01-01 00:00:00.710105 | aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa |      FATAL | Check Keystone public endpoint status | overcloud-controller-0 -> localhost | item=placement | error={"ansible_job_id": "000000000000.000000", "ansible_loop_var": "tripleo_keystone_resources_endpoint_async_result_item", "attempts": 2, "changed": false, "cmd": "/tmp/ansible-tripleo-admin/ansible-tmp-0000000000.0000000-000000-00000000000000/AnsiballZ_endpoint.py", "data": "", "finished": 1, "msg": "Traceback (most recent call last):\n  File \"/tmp/ansible_async_wrapper_payload_dborq437/ansible_async_wrapper_payload.zip/ansible/modules/utilities/logic/async_wrapper.py\", line 166, in _run_module\n  File \"/tmp/ansible_async_wrapper_payload_dborq437/ansible_async_wrapper_payload.zip/ansible/modules/utilities/logic/async_wrapper.py\", line 94, in _filter_non_json_lines\nValueError: No start of json char found\n", "stderr": "Failed to discover available identity versions when contacting https://overcloud.example.com:13000. Attempting to parse version from URL.\nTraceback (most recent call last):\n  File \"/usr/lib/python3.6/site-packages/urllib3/connection.py\", line 162, in _new_conn\n    (self._dns_host, self.port), self.timeout, **extra_kw)\n  File \"/usr/lib/python3.6/site-packages/urllib3/util/connection.py\", line 57, in create_connection\n    for res in socket.getaddrinfo(host, port, family, socket.SOCK_STREAM):\n  File \"/usr/lib64/python3.6/socket.py\", line 745, in getaddrinfo\n    for res in _socket.getaddrinfo(host, port, family, type, proto, flags):\nsocket.gaierror: [Errno -2] Name or service not known\n\nDuring handling of the above exception, another exception occurred:\n\nTraceback (most recent call last):\n  File \"/usr/lib/python3.6/site-packages/urllib3/connectionpool.py\", line 600, in urlopen\n    chunked=chunked)\n  File \"/usr/lib/python3.6/site-packages/urllib3/connectionpool.py\", line 343, in _make_request\n    self._validate_conn(conn)\n  File \"/usr/lib/python3.6/site-packages/urllib3/connectionpool.py\", line 839, in _validate_conn\n    conn.connect()\n  File \"/usr/lib/python3.6/site-packages/urllib3/connection.py\", line 315, in connect\n    conn = self._new_conn()\n  File \"/usr/lib/python3.6/site-packages/urllib3/connection.py\", line 171, in _new_conn\n    self, \"Failed to establish a new connection: %s\" % e)\nurllib3.exceptions.NewConnectionError: <urllib3.connection.VerifiedHTTPSConnection object at 0x000000000000>: Failed to establish a new connection: [Errno -2] Name or service not known  ........
  

• overcloud.example.com is defined in the CloudName parameter in the template files.

  $ cat templates/cloudname.yaml
  parameter_defaults:
    CloudName: overcloud.example.com
    DnsServers: ["10.0.0.1"]