Removed asynctestcase.py (#14444)

sdk/tables/azure-data-tables/tests/_shared/asynctestcase.py

@@ -29,19 +29,6 @@ async def get_token(self, *args):
 
 class AsyncTableTestCase(TableTestCase):
     @staticmethod
-    def await_prepared_test(test_fn):
-        """Synchronous wrapper for async test methods. Used to avoid making changes
-        upstream to AbstractPreparer (which doesn't await the functions it wraps)
-        """
-
-        @functools.wraps(test_fn)
-        def run(test_class_instance, *args, **kwargs):
-            trim_kwargs_from_test_function(test_fn, kwargs)
-            loop = asyncio.get_event_loop()
-            return loop.run_until_complete(test_fn(test_class_instance, **kwargs))
-
-        return run
-
     def generate_oauth_token(self):
         if self.is_live:
             from azure.identity.aio import ClientSecretCredential