[#5771] remove another Response constant

Author: xabbuh

book/http_cache.rst

@@ -912,7 +912,7 @@ Here is how you can configure the Symfony reverse proxy to support the
             if ('127.0.0.1' !== $request->getClientIp()) {
                 return new Response(
                     'Invalid HTTP method',
-                    Response::HTTP_BAD_REQUEST
+                    400
                 );
             }