Move audit event types topic to better location on global navigation

What does this MR do and why?

After discussion, it became clear that the audit event types are a more generic that aren't just for streaming. This MR updates the layout of the global navigation to reflect that fact.

Screenshots, screen recordings, or links to review app

• Before: https://docs.gitlab.com/ee/administration/audit_event_streaming/audit_event_types.html
• After: https://eread-move-audit-event-types-to-better-location-on-nav.docs.gitlab-review.app/ee/administration/audit_event_streaming/audit_event_types.html

Merge request acceptance checklist

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• I have evaluated the MR acceptance checklist for this merge request.