orig dst: add support for port override (#23040)

Signed-off-by: Brian Sonnenberg <bsonnenberg@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ 81cb61020303a1dc824d90e1183f1f485d452026

envoy/config/cluster/v3/cluster.proto

@@ -546,6 +546,10 @@ message Cluster {
     // The http header to override destination address if :ref:`use_http_header <envoy_v3_api_field_config.cluster.v3.Cluster.OriginalDstLbConfig.use_http_header>`.
     // is set to true. If the value is empty, :ref:`x-envoy-original-dst-host <config_http_conn_man_headers_x-envoy-original-dst-host>` will be used.
     string http_header_name = 2;
+
+    // The port to override for the original dst address. This port
+    // will take precedence over filter state and header override ports
+    google.protobuf.UInt32Value upstream_port_override = 3 [(validate.rules).uint32 = {lte: 65535}];
   }
 
   // Common configuration for all load balancer implementations.