refactor: Update ProviderOpenAIOfficial to skip test message when TEST_MODE=on

This commit updates the `ProviderOpenAIOfficial` class to skip returning the test message when the environment variable `TEST_MODE` is set to "on". This change ensures that the test message is only returned when both `TEST_LLM` and `TEST_MODE` are set to "on".

model/provider/openai_official.py

@@ -296,7 +296,7 @@ class ProviderOpenAIOfficial(Provider):
                         extra_conf: Dict = None,
                         **kwargs
                     ) -> str:
-        if os.environ.get("TEST_LLM", "off") != "on":
+        if os.environ.get("TEST_LLM", "off") != "on" and os.environ.get("TEST_MODE", "off") == "on":
             return "这是一个测试消息。"
         
         super().accu_model_stat()