refactor: remove unused code

Endpoint/Configuration/Core/Middleware/MaintenanceModeMiddleware.cs

@@ -30,8 +30,6 @@ public class MaintenanceModeMiddleware(RequestDelegate next, IMaintenanceModeSer
 
             throw new ServerUnavailableException(
                 "The service is currently not configured. Go to the setup page if you are an administrator or try again later.", false);
-
-            await context.Response.WriteAsync(error);
         }
     }
 }