Make speech streaming default to SSE (#4679)

Signed-off-by: syd520zy <529477025@qq.com>

tests/helpers/runtime.py

@@ -1770,6 +1770,7 @@ class OpenAIClientHandler:
             "seed",
             "instructions",
             "speed",
+            "stream_format",
         ):
             if key in request_config:
                 extra_body[key] = request_config[key]