Description of problem:

It looks like the `Invalid PIS leads to degraded MCN in a standard Pool` test failed a few times this past weekend in runs of the `periodic-ci-openshift-release-master-nightly-4.20-e2e-metal-ipi-ovn-serial-virtualmedia-1of2` test suite. This has caused a red component readiness alert for PinnedImageSets.

Version-Release number of selected component (if applicable):

I've only checked 4.20.

How reproducible:

Unsure–it seems like this test has passed before & after this past weekend, so these failures may be a flake.

Steps to Reproduce:

• To see all runs of the `periodic-ci-openshift-release-master-nightly-4.20-e2e-metal-ipi-ovn-serial-virtualmedia-1of2` test: https://sippy.dptools.openshift.org/sippy-ng/jobs/4.20/runs?filters=%7B%22items%22%3A%5B%7B%22columnField%22%3A%22job%22%2C%22operatorValue%22%3A%22equals%22%2C%22value%22%3A%22periodic-ci-openshift-release-master-nightly-4.20-e2e-metal-ipi-ovn-serial-virtualmedia-1of2%22%7D%5D%7D
• To see an example of a test run with a PIS failure: https://prow.ci.openshift.org/view/gs/test-platform-results/logs/periodic-ci-openshift-release-master-nightly-4.20-e2e-metal-ipi-ovn-serial-virtualmedia-1of2/1956794949517185024

Actual results:

The PIS test sometimes fails and now has a metal pass rate of 94.4%, which is lower than the required 95% pass rate.

Expected results:

All tests should meet the component readiness criteria.

Additional info:

See related Slack thread here.