[buffer filter] Remove max_request_time field and code (#5486)

Signed-off-by: Auni Ahsan <auni@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ 0986e33e1ff1ebefd98597b1a472b9c1a9c8ad81

envoy/config/filter/http/buffer/v2/buffer.proto

@@ -15,16 +15,11 @@ import "gogoproto/gogo.proto";
 // Buffer :ref:`configuration overview <config_http_filters_buffer>`.
 
 message Buffer {
+  reserved 2; // formerly max_request_time
+
   // The maximum request size that the filter will buffer before the connection
   // manager will stop buffering and return a 413 response.
   google.protobuf.UInt32Value max_request_bytes = 1 [(validate.rules).uint32.gt = 0];
-
-  // The maximum number of seconds that the filter will wait for a complete
-  // request before returning a 408 response.
-  // deprecated in favor of http connection manager of :ref:request timeouts
-  // <envoy_api_field_config.filter.network.http_connection_manager.v2.HttpConnectionManager.request_timeout>
-  google.protobuf.Duration max_request_time = 2
-      [deprecated = true, (validate.rules).duration = {gt: {}}, (gogoproto.stdduration) = true];
 }
 
 message BufferPerRoute {