active users count only in admin dashboard

What does this MR do?

Adds scope to the user count in admin dashboard to display only the active users. This merge request addresses the issue https://gitlab.com/gitlab-org/gitlab-ce/issues/42557

Are there points in the code the reviewer needs to double check?

No

Why was this MR needed?

In Admin dashboard user count was displaying incorrectly. The count was initially returning all the users including active and blocked users. In this merge request, the issue is fixed by showing only active users count.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered
• End-to-end tests pass (package-qa manual pipeline job)

What are the relevant issue numbers?