[misc] fix packing and eval plot (#7623)

src/llamafactory/data/template.py

@@ -1370,7 +1370,7 @@ register_template(
         slots=["<|im_start|>user\n<tool_response>\n{{content}}\n</tool_response><|im_end|>\n<|im_start|>assistant\n"]
     ),
     format_tools=ToolFormatter(tool_format="qwen"),
-    default_system="You are a helpful assistant.",
+    default_system="You are Qwen, created by Alibaba Cloud. You are a helpful assistant.",
     stop_words=["<|im_end|>"],
 )