Followup changes for `OrcaLoadReport` handling in `Router::Filter`. (#35952)

Commit Message:

Followup changes for `OrcaLoadReport` handling in `Router::Filter`.

- Use ENVOY_STREAM_LOG in `Router::Filter::maybeProcessOrcaLoadReport`.
- Add Integration test for custom metrics.
- Update CNCF version to bring in `OrcaLoadReport` proto changes.
- Add references to `OrcaLoadReport` proto.

Risk Level: low
Docs Changes:
Release Notes:
#34777

---------

Signed-off-by: Misha Efimov <mef@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ 4ba73c869963cbf1d1afe8f4a4f568783fb1c750

BUILD

@@ -382,6 +382,7 @@ proto_library(
     visibility = ["//visibility:public"],
     deps = [
         "@com_github_cncf_xds//xds/core/v3:pkg",
+        "@com_github_cncf_xds//xds/data/orca/v3:pkg",
         "@com_github_cncf_xds//xds/type/matcher/v3:pkg",
         "@com_github_cncf_xds//xds/type/v3:pkg",
     ],

bazel/repository_locations.bzl

@@ -52,9 +52,9 @@ REPOSITORY_LOCATIONS_SPEC = dict(
         project_desc = "xDS API Working Group (xDS-WG)",
         project_url = "https://github.com/cncf/xds",
         # During the UDPA -> xDS migration, we aren't working with releases.
-        version = "555b57ec207be86f811fb0c04752db6f85e3d7e2",
-        sha256 = "0c8c4f0f67fed967b51049f7d5e2ca7a9bd433970a29c88e272c8665328172f5",
-        release_date = "2024-04-23",
+        version = "b4127c9b8d78b77423fd25169f05b7476b6ea932",
+        sha256 = "aa5f1596bbef3f277dcf4700e4c1097b34301ae66f3b79cd731e3adfbaff2f8f",
+        release_date = "2024-09-05",
         strip_prefix = "xds-{version}",
         urls = ["https://github.com/cncf/xds/archive/{version}.tar.gz"],
         use_category = ["api"],

envoy/config/cluster/v3/cluster.proto

@@ -1162,14 +1162,13 @@ message Cluster {
   // from the LRS stream here.]
   core.v3.ConfigSource lrs_server = 42;
 
-  // [#not-implemented-hide:]
-  // A list of metric names from ORCA load reports to propagate to LRS.
+  // A list of metric names from :ref:`ORCA load reports <envoy_v3_api_msg_.xds.data.orca.v3.OrcaLoadReport>` to propagate to LRS.
   //
   // If not specified, then ORCA load reports will not be propagated to LRS.
   //
   // For map fields in the ORCA proto, the string will be of the form ``<map_field_name>.<map_key>``.
   // For example, the string ``named_metrics.foo`` will mean to look for the key ``foo`` in the ORCA
-  // ``named_metrics`` field.
+  // :ref:`named_metrics <envoy_v3_api_field_.xds.data.orca.v3.OrcaLoadReport.named_metrics>` field.
   //
   // The special map key ``*`` means to report all entries in the map (e.g., ``named_metrics.*`` means to
   // report all entries in the ORCA named_metrics field). Note that this should be used only with trusted