[logspam] Remove unguarded INFO logging of xds node ID (#37405)

Closes #37405

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/37405 from drfloob:logspam/xds_client 73c02c5b40
PiperOrigin-RevId: 660120253

src/core/xds/xds_client/xds_client.cc

@@ -1564,8 +1564,9 @@ XdsClient::XdsClient(
   }
   CHECK(bootstrap_ != nullptr);
   if (bootstrap_->node() != nullptr) {
-    LOG(INFO) << "[xds_client " << this
-              << "] xDS node ID: " << bootstrap_->node()->id();
+    GRPC_TRACE_LOG(xds_client, INFO)
+        << "[xds_client " << this
+        << "] xDS node ID: " << bootstrap_->node()->id();
   }
 }