Use custom _sleep function

Author: pquentin

elasticsearch/_async/helpers.py

@@ -256,9 +256,7 @@ async def map_actions() -> AsyncIterable[_TYPE_BULK_ACTION_HEADER_AND_BODY]:
                 ]
             ] = []
             if attempt:
-                await anyio.sleep(
-                    min(max_backoff, initial_backoff * 2 ** (attempt - 1))
-                )
+                await _sleep(min(max_backoff, initial_backoff * 2 ** (attempt - 1)))
 
             try:
                 data: Union[