Prevent logged in user from blocking themselves in abuse reports

What does this MR do and why?

• Resolves https://gitlab.com/gitlab-org/modelops/anti-abuse/team-tasks/-/issues/185
• If an admin has been reported for abuse, they should not be allowed to take action on that report. They can continue to block/report other admins.

Screenshots or screen recordings

How to set up and validate locally

1. Log-in as any user that is not root. Go to the admin profile, /root and report the user for abuse
2. Log back in as root and navigate to the abuse reports, http://127.0.0.1:3000/admin/abuse_reports

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

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