Prevent health checks warnings for disabled notifications

(cherry picked from commit 5a7f42a63e25d6abdb187c37e92a908a6b85fb4d)

src/NzbDrone.Core/Notifications/NotificationFactory.cs

@@ -36,6 +36,11 @@ namespace NzbDrone.Core.Notifications
             _logger = logger;
         }
 
+        protected override List<NotificationDefinition> Active()
+        {
+            return base.Active().Where(c => c.Enable).ToList();
+        }
+
         public List<INotification> OnGrabEnabled(bool filterBlockedNotifications = true)
         {
             if (filterBlockedNotifications)