ratelimit: be able to disable x-envoy-ratelimited response header sent (#13270)

Signed-off-by: András Czigány <andras.czigany@strivacity.com>

Mirrored from https://github.com/envoyproxy/envoy @ dc3460c247538b8f81d49bd7984f46d142f20ba9

envoy/extensions/filters/http/ratelimit/v3/rate_limit.proto

@@ -19,7 +19,7 @@ option (udpa.annotations.file_status).package_version_status = ACTIVE;
 // Rate limit :ref:`configuration overview <config_http_filters_rate_limit>`.
 // [#extension: envoy.filters.http.ratelimit]
 
-// [#next-free-field: 9]
+// [#next-free-field: 10]
 message RateLimit {
   option (udpa.annotations.versioning).previous_message_type =
       "envoy.config.filter.http.rate_limit.v2.RateLimit";
@@ -60,7 +60,6 @@ message RateLimit {
   // The filter's behaviour in case the rate limiting service does
   // not respond back. When it is set to true, Envoy will not allow traffic in case of
   // communication failure between rate limiting service and the proxy.
-  // Defaults to false.
   bool failure_mode_deny = 5;
 
   // Specifies whether a `RESOURCE_EXHAUSTED` gRPC code must be returned instead
@@ -99,6 +98,11 @@ message RateLimit {
   // Disabled by default.
   XRateLimitHeadersRFCVersion enable_x_ratelimit_headers = 8
       [(validate.rules).enum = {defined_only: true}];
+
+  // Disables emitting the :ref:`x-envoy-ratelimited<config_http_filters_router_x-envoy-ratelimited>` header
+  // in case of rate limiting (i.e. 429 responses).
+  // Having this header not present potentially makes the request retriable.
+  bool disable_x_envoy_ratelimited_header = 9;
 }
 
 message RateLimitPerRoute {