Fix line length violation in streaming delta comment

Shorten comment from 81 to 71 characters to comply with E501 line length limit.
The comment 'Log individual streaming delta if output logging is enabled'
was shortened to 'Log streaming delta if output logging is enabled' while
maintaining clarity and meaning.

Signed-off-by: Adrian Garcia <adrian.garcia@inceptionai.ai>

Author: mizadri

vllm/entrypoints/openai/serving_chat.py

@@ -825,7 +825,7 @@ async def chat_completion_stream_generator(
                     if delta_message is None:
                         continue
 
-                    # Log individual streaming delta if output logging is enabled
+                    # Log streaming delta if output logging is enabled
                     if self.enable_log_outputs and self.request_logger:
                         delta_content = ""
                         if delta_message.content: