test_network_policies cannot reachout to nginex with restrictions for 30 min

[Alexander Balderson]

Running k8s 1.28.2 on focal baremetal with calico as the CNI. The test "test_network_policies" ran for 30 min without getting the proper response when running with restrictions. The test, however, when run without restrictions succeeded within 30 seconds.

This test was run on an older version of the test suite d069605, but there doesnt look to be any changes to the test code since that commit.

The testrun can be found at:
https://solutions.qa.canonical.com/testruns/ccb5dc24-6e2f-437a-96b9-cd98f966c866/
and the crashdump for the k8s layer can be found at:
https://oil-jenkins.canonical.com/artifacts/ccb5dc24-6e2f-437a-96b9-cd98f966c866/generated/generated/kubernetes-maas/juju-crashdump-kubernetes-maas-2023-09-23-08.33.17.tar.gz
and all logs at:
https://oil-jenkins.canonical.com/artifacts/ccb5dc24-6e2f-437a-96b9-cd98f966c866/index.html

All occurrences of this bug can be found at:
https://solutions.qa.canonical.com/bugs/2037441