revert elevenlabs example changes

examples/foundational/07d-interruptible-elevenlabs.py

@@ -48,7 +48,6 @@ async def main():
         tts = ElevenLabsTTSService(
             api_key=os.getenv("ELEVENLABS_API_KEY", ""),
             voice_id=os.getenv("ELEVENLABS_VOICE_ID", ""),
-            model="eleven_flash_v2_5",
         )
 
         llm = OpenAILLMService(api_key=os.getenv("OPENAI_API_KEY"), model="gpt-4o")
@@ -80,7 +79,7 @@ async def main():
                 allow_interruptions=True,
                 enable_metrics=True,
                 enable_usage_metrics=True,
-                # report_only_initial_ttfb=True,
+                report_only_initial_ttfb=True,
             ),
         )