transports(daily): no need for joining flag

This was put back because of an issue in ParallelPipeline but that issue is now
fixed so the joining check is not really necessary.

src/pipecat/transports/services/daily.py

@@ -200,7 +200,6 @@ class DailyTransportClient(EventHandler):
         self._other_participant_has_joined = False
 
         self._joined = False
-        self._joining = False
         self._leave_counter = 0
 
         self._executor = ThreadPoolExecutor(max_workers=5)
@@ -315,12 +314,11 @@ class DailyTransportClient(EventHandler):
 
     async def join(self):
         # Transport already joined, ignore.
-        if self._joined or self._joining:
+        if self._joined:
             # Increment leave counter if we already joined.
             self._leave_counter += 1
             return
 
-        self._joining = True
         logger.info(f"Joining {self._room_url}")
 
         # For performance reasons, never subscribe to video streams (unless a
@@ -353,7 +351,6 @@ class DailyTransportClient(EventHandler):
             error_msg = f"Time out joining {self._room_url}"
             logger.error(error_msg)
             await self._callbacks.on_error(error_msg)
-        self._joining = False
 
     async def _start_transcription(self):
         if not self._token: