This PR does the below:

• updates slurm gcp tag from 6.10.1 to 6.10.5 as a4x support for managed lustre is introduced in 6.10.5
• adds managed lustre as an option in the A4X blueprint.
• fixes enroot configuration in a4x image and a4x nodeset startup script

Submission Checklist

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• 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 #