[core] add actor labels to export events (#51687)

We added the `labels` field to actor in
https://github.com/ray-project/ray/pull/48715/files. This PR populates
this field to the export events.

Test:
- CI
- Check that `labels` field are exported successfully

<img width="676" alt="Screenshot 2025-03-25 at 2 37 37 PM"
src="https://github.com/user-attachments/assets/5879229d-2d06-4a76-8a25-3afcdd0d63a0"
/>

---------

Signed-off-by: can <can@anyscale.com>

Author: can-anyscale

src/ray/gcs/gcs_server/gcs_actor_manager.cc

@@ -272,6 +272,8 @@ void GcsActor::WriteActorExportEvent() const {
   export_actor_data_ptr->set_node_id(actor_table_data_.node_id());
   export_actor_data_ptr->set_placement_group_id(actor_table_data_.placement_group_id());
   export_actor_data_ptr->set_repr_name(actor_table_data_.repr_name());
+  export_actor_data_ptr->mutable_labels()->insert(task_spec_.get()->labels().begin(),
+                                                  task_spec_.get()->labels().end());
 
   RayExportEvent(export_actor_data_ptr).SendEvent();
 }

src/ray/gcs/gcs_server/test/export_api/gcs_actor_manager_export_event_test.cc

@@ -269,6 +269,7 @@ TEST_F(GcsActorManagerTest, TestBasic) {
   rpc::CreateActorRequest create_actor_request;
   create_actor_request.mutable_task_spec()->CopyFrom(
       registered_actor->GetCreationTaskSpecification().GetMessage());
+  create_actor_request.mutable_task_spec()->mutable_labels()->insert({"w00t", "hi"});
   RAY_CHECK_EQ(
       gcs_actor_manager_->CountFor(rpc::ActorTableData::DEPENDENCIES_UNREADY, ""), 1);
 
@@ -319,6 +320,9 @@ TEST_F(GcsActorManagerTest, TestBasic) {
               "The actor is dead because all references to the actor were removed "
               "including lineage ref count.");
         }
+        if (expected_states[event_idx] == "ALIVE") {
+          ASSERT_EQ(event_data["labels"]["w00t"], "hi");
+        }
       }
       return;
     } else {

src/ray/protobuf/export_api/export_actor_data.proto

@@ -73,4 +73,6 @@ message ExportActorData {
   // might depend on actor fields to be initialized in __init__.
   // Default to empty string if no customized repr is defined.
   string repr_name = 14;
+  // The key-value labels for task and actor.
+  map<string, string> labels = 15;
 }