Remove CephFS from example

What does this MR do?

We recommend against using CephFS in https://docs.gitlab.com/ee/administration/high_availability/nfs.html#avoid-using-cephfs-and-glusterfs

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry for user-facing changes, or community contribution. Check the link for other scenarios.
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content