FIX: Admin problem notification minor issues (#24963)

* Icon was a gift and not exclamation-triangle...these admin problems
  are not usually a gift :P
* Added missing title translation

app/assets/javascripts/discourse/app/lib/notification-types/admin-problems.js

@@ -16,6 +16,6 @@ export default class extends NotificationTypeBase {
   }
 
   get icon() {
-    return "gift";
+    return "exclamation-triangle";
   }
 }

config/locales/client.en.yml

@@ -2680,6 +2680,7 @@ en:
         reaction: "new reaction"
         votes_released: "Vote was released"
         new_features: "new Discourse features have been released!"
+        admin_problems: "new advice on your site dashboard"
 
     upload_selector:
       uploading: "Uploading"