Remove admin user count from Users statistics

What does this MR do?

Part of #118592 (closed)

Admin users can be listed twice in the Users statistics in the Admin Area. Once in the admin users count and also in the numbers for Users with highest role statistics. In preparation for the implementation of summary lines with #118592 (closed) we're removing the Admin users count or numbers won't add up.

Screenshots

Before	After

Does this MR meet the acceptance criteria?

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