No pagination on abuse_reports

We removed

    = paginate @abuse_reports

from app/views/admin/abuse_reports/index.html.haml in https://gitlab.com/gitlab-org/gitlab-ee/commit/1e6d8a388c3e818ee63daabb3b05b0c30f4502fe

This removed the ability to paginate through the abuse pages

//cc @lbennett @briann