fixes #2517: Janitor trial report broken

app/logical/reports/janitor_trials.rb

@@ -11,6 +11,10 @@ module Reports
         JanitorTrial.where(user_id: user.id).first
       end
 
+      def created_at
+        trial.created_at
+      end
+
       def since
         3.months.ago
       end