Use BaseEventLoop._thread_id instead of a custom attribute (#124054)

Co-authored-by: J. Nick Koston <nick@koston.org>

homeassistant/runner.py

@@ -107,7 +107,6 @@ class HassEventLoopPolicy(asyncio.DefaultEventLoopPolicy):
     def new_event_loop(self) -> asyncio.AbstractEventLoop:
         """Get the event loop."""
         loop: asyncio.AbstractEventLoop = super().new_event_loop()
-        setattr(loop, "_thread_ident", threading.get_ident())
         loop.set_exception_handler(_async_loop_exception_handler)
         if self.debug:
             loop.set_debug(True)