Use tag filter for pending tag count on admin dashboard (#36404)

app/controllers/admin/dashboard_controller.rb

@@ -9,10 +9,16 @@ module Admin
 
       @pending_appeals_count = Appeal.pending.async_count
       @pending_reports_count = Report.unresolved.async_count
-      @pending_tags_count    = Tag.pending_review.async_count
+      @pending_tags_count    = pending_tags.async_count
       @pending_users_count   = User.pending.async_count
       @system_checks         = Admin::SystemCheck.perform(current_user)
       @time_period           = (29.days.ago.to_date...Time.now.utc.to_date)
     end
+
+    private
+
+    def pending_tags
+      ::Trends::TagFilter.new(status: :pending_review).results
+    end
   end
 end