Local rate limit - add rate_limited_as_resource_exhausted flag (#29279)

* Local rate limit - add rate_limited_as_resource_exhausted flag to change grpc status code

Signed-off-by: Pawan Kumar <pawanbishnoi@outlook.com>

Signed-off-by: Pawan Bishnoi <pawanbishnoi@outlook.com>

* fix minor renaming error

Signed-off-by: Pawan Bishnoi <pawanbishnoi@outlook.com>

* fix precheck error

Signed-off-by: Pawan Bishnoi <pawanbishnoi@outlook.com>

* add test

Signed-off-by: Pawan Bishnoi <pawanbishnoi@outlook.com>

* fix format and typo

Signed-off-by: Pawan Bishnoi <pawanbishnoi@outlook.com>

* review comments

Signed-off-by: Pawan Bishnoi <pawanbishnoi@outlook.com>

---------

Signed-off-by: Pawan Bishnoi <pawanbishnoi@outlook.com>

Mirrored from https://github.com/envoyproxy/envoy @ 88a80e6bbbee56de8c3899c75eaf36c46fad1aa7

envoy/extensions/filters/http/local_ratelimit/v3/local_rate_limit.proto

@@ -22,7 +22,7 @@ option (udpa.annotations.file_status).package_version_status = ACTIVE;
 // Local Rate limit :ref:`configuration overview <config_http_filters_local_rate_limit>`.
 // [#extension: envoy.filters.http.local_ratelimit]
 
-// [#next-free-field: 15]
+// [#next-free-field: 16]
 message LocalRateLimit {
   // The human readable prefix to use when emitting stats.
   string stat_prefix = 1 [(validate.rules).string = {min_len: 1}];
@@ -125,4 +125,9 @@ message LocalRateLimit {
   // no matching descriptor. If set to true, default token bucket will always
   // be consumed. Default is true.
   google.protobuf.BoolValue always_consume_default_token_bucket = 14;
+
+  // Specifies whether a ``RESOURCE_EXHAUSTED`` gRPC code must be returned instead
+  // of the default ``UNAVAILABLE`` gRPC code for a rate limited gRPC call. The
+  // HTTP code will be 200 for a gRPC response.
+  bool rate_limited_as_resource_exhausted = 15;
 }