Add Auditor as a filter option to the Admin users page

What does this MR do and why?

Re-adding !187612 (merged) after DB query has been addressed by !192036 (merged).

Adds Auditor as a filter option to the Admin users page

Changelog: changed
EE: true

References

List auditors in /admin/users (#353272 - closed)

Screenshots or screen recordings

Before	After

How to set up and validate locally

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