replacing centos7 with rocky8 in nfs-server modules

[RachaelSTamakloe]

Submission Checklist

Please take the following actions before submitting this pull request.

• Fork your PR branch from the Toolkit "develop" branch (not main)
• Test all changes with pre-commit in a local branch #
• Confirm that "make tests" passes all tests
• Add or modify unit tests to cover code changes
• Ensure that unit test coverage remains above 80%
• Update all applicable documentation
• Follow Cluster Toolkit Contribution guidelines #

[rohitramu]

I've triggered the hcls test, as it uses the nfs-server module. I will approve, but please ensure this test passes before merging.