ratelimit: remove deprecated cluster (#5185)

Signed-off-by: Rama Chavali <rama.rao@salesforce.com>

Mirrored from https://github.com/envoyproxy/envoy @ 96b575469dceb640e5f14e7e454f5ed0f91b3d2f

envoy/config/ratelimit/v2/rls.proto

@@ -11,22 +11,12 @@ import "validate/validate.proto";
 
 // Rate limit :ref:`configuration overview <config_rate_limit_service>`.
 message RateLimitServiceConfig {
-  oneof service_specifier {
-    option (validate.required) = true;
+  reserved 1;
 
-    // Specifies the cluster manager cluster name that hosts the rate limit
-    // service. The client will connect to this cluster when it needs to make
-    // rate limit service requests. This field is deprecated and `grpc_service`
-    // should be used instead. The :ref:`Envoy gRPC client
-    // <envoy_api_field_core.GrpcService.envoy_grpc>` will be used when this field is
-    // specified.
-    string cluster_name = 1 [(validate.rules).string.min_bytes = 1, deprecated = true];
-
-    // Specifies the gRPC service that hosts the rate limit service. The client
-    // will connect to this cluster when it needs to make rate limit service
-    // requests.
-    envoy.api.v2.core.GrpcService grpc_service = 2;
-  }
+  // Specifies the gRPC service that hosts the rate limit service. The client
+  // will connect to this cluster when it needs to make rate limit service
+  // requests.
+  envoy.api.v2.core.GrpcService grpc_service = 2 [(validate.rules).message.required = true];
 
   reserved 3;
 }