Use limit parameter rather than hardcoded value in `ldap:check` rake task

Originally opened at !4788 (closed) by @rickettm.

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What does this MR do?

Fix bug #15344 (closed), so that the limit parameter that is already passed in to the print_users function is actually used, rather than using a hardcoded value.

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

No, it is a trivial change.

Why was this MR needed?

This bug causes 100 LDAP users to be displayed even when a different limit is given, which can be annoying.

What are the relevant issue numbers?

Fixes #15344 (closed).

Does this MR meet the acceptance criteria?

• CHANGELOG entry added
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together