[cpp worker] support cluster mode (#9977)

python/ray/services.py

@@ -1484,9 +1484,14 @@ def build_cpp_worker_command(
     Returns:
         The command string for starting CPP worker.
     """
+
+    # TODO(Guyang Song): Remove the arg is_default_worker.
+    # See `cluster_mode_test.cc` for why this workaround is currently needed
+    # for C++ workers.
     command = [
         DEFAULT_WORKER_EXECUTABLE, plasma_store_name, raylet_name,
-        str(node_manager_port), redis_password, session_dir
+        str(node_manager_port), redis_address, redis_password, session_dir,
+        "is_default_worker"
     ]
 
     return command