Find the max limit for users count on free user cap

What does this MR do and why?

• finds the max limit to be used by the limit for the database queries.
• We need to use this since we want to only run the full_users_count once per request, which we do. So we need to find the max limit setting from all of our possible dashboard_*limit settings so that our comparisons for notification and enforcement will always work as we expect.
  • before this change we'd only get back a max possible users_count that matched the first users_count query that was performed. That limit used in the first users_count could be Enforcement or Notification depending on feature flags or placement in the stack. This could cause scenarios where our comparison with users_count would yield false positives/negatives due to their individual definition of limit when comparing to users_count.
  • after this change we'll get back the max of those entries so that we'll always have true comparison results.

MR acceptance checklist

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

Related to #383264