Update dialogue_manager: remove useless import

dialogue_manager.py

@@ -18,8 +18,6 @@ from history_dialogue_service import HistoryDialogueService
 
 from chat_service import ChatServiceType
 from message import MessageType, Message
-# from vector_memory_manager import VectorMemoryManager
-from structured_memory_manager import StructuredMemoryManager
 from user_manager import UserManager
 from prompt_templates import *