VMs occasionally fail to connect to metadata server for cloud-init

Issue

• From the ovn metadata agent logs:

ovn-metadata-agent.log.2.gz:2021-07-28 12:46:39.100 35880 INFO networking_ovn.agent.metadata.agent [-] Cleaning up ovnmeta-93e85d05-2812-4cf0-ae2f-25d4ec4980ee namespace which is not needed anymore
ovn-metadata-agent.log.3.gz:2021-07-27 19:18:05.238 35880 INFO networking_ovn.agent.metadata.agent [-] Port 14fd1c31-de47-4b7b-b5d6-a97b821401e7 in datapath 93e85d05-2812-4cf0-ae2f-25d4ec4980ee bound to our chassis
ovn-metadata-agent.log.3.gz:2021-07-27 19:36:23.294 35880 INFO networking_ovn.agent.metadata.agent [-] Port 14fd1c31-de47-4b7b-b5d6-a97b821401e7 in datapath 93e85d05-2812-4cf0-ae2f-25d4ec4980ee unbound from our chassis
ovn-metadata-agent.log.3.gz:2021-07-27 19:36:23.298 35880 INFO networking_ovn.agent.metadata.agent [-] Cleaning up ovnmeta-93e85d05-2812-4cf0-ae2f-25d4ec4980ee namespace which is not needed anymore
ovn-metadata-agent.log.3.gz:2021-07-27 19:39:12.092 35880 INFO networking_ovn.agent.metadata.agent [-] Port dc316481-3f23-4c87-aded-1ac6a4138ad8 in datapath 93e85d05-2812-4cf0-ae2f-25d4ec4980ee bound to our chassis

• VM cloud-init.log

2021-07-29 20:40:02,792 - url_helper.py[DEBUG]: Calling 'http://169.254.169.254/openstack' failed [10/-1s]: request error [HTTPConnectionPool(host='169.254.169.254', port=80): Max retries exceeded with url: /openstack (Caused by ConnectTimeoutError(<urllib3.connection.HTTPConnection object at 0x7fdbd45e31d0>, 'Connection to 169.254.169.254 timed out. (connect timeout=10.0)'))]
2021-07-29 20:40:02,792 - DataSourceOpenStack.py[DEBUG]: Giving up on OpenStack md from ['http://169.254.169.254/openstack'] after 10 seconds
2021-07-29 20:40:02,792 - util.py[DEBUG]: Crawl of metadata service took 70.087 seconds

2021-07-29 20:40:02,801 - util.py[WARNING]: No active metadata service found
2021-07-29 20:40:02,801 - util.py[DEBUG]: No active metadata service found
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/cloudinit/sources/DataSourceOpenStack.py", line 134, in _get_data
    func=self._crawl_metadata)
  File "/usr/lib/python2.7/site-packages/cloudinit/util.py", line 2540, in log_time
    ret = func(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/cloudinit/sources/DataSourceOpenStack.py", line 177, in _crawl_metadata
    'No active metadata service found')
InvalidMetaDataException: No active metadata service found