[Bug]: When apply continue_final_message for OpenAI server, the "echo":false is ignored (#10180)

Signed-off-by: chaunceyjiang <chaunceyjiang@gmail.com>

vllm/entrypoints/openai/serving_chat.py

@@ -361,7 +361,7 @@ class OpenAIServingChat(OpenAIServing):
 
                     # Send response to echo the input portion of the
                     # last message
-                    if request.echo or request.continue_final_message:
+                    if request.echo:
                         last_msg_content: Union[str, List[Dict[str, str]]] = ""
                         if conversation and "content" in conversation[
                                 -1] and conversation[-1].get("role") == role:
@@ -706,7 +706,7 @@ class OpenAIServingChat(OpenAIServing):
                 stop_reason=output.stop_reason)
             choices.append(choice_data)
 
-        if request.echo or request.continue_final_message:
+        if request.echo:
             last_msg_content: Union[str, List[Dict[str, str]]] = ""
             if conversation and "content" in conversation[-1] and conversation[
                     -1].get("role") == role: