api-csds: Propose a boolean field in ClientStatusRequest to indicate whether xds server should exclude detailed config(xds_config field in GenericXdsConfig) but keep the rest of fields in response (#27880)

Signed-off-by: jaychenatr <jiechen@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ de3ae4a6e996ef7e6356c62b44990a6cf01e3a1c

envoy/service/status/v3/csds.proto

@@ -85,6 +85,11 @@ message ClientStatusRequest {
 
   // The node making the csds request.
   config.core.v3.Node node = 2;
+
+  // If true, the server will not include the resource contents in the response
+  // (i.e., the generic_xds_configs.xds_config field will not be populated).
+  // [#not-implemented-hide:]
+  bool exclude_resource_contents = 3;
 }
 
 // Detailed config (per xDS) with status.