Partially revert

There is no such thing as a "tuple comprehension":
https://stackoverflow.com/questions/52285419/aggregating-an-async-generator-to-a-tuple#52285420

Fixes CI error:
FAILED tests/test_group.py::test_create_hierarchy_existing_nodes[zarr2-async-array-memory] - TypeError: 'async_generator' object is not iterable

Author: DimitriPapadopoulos

tests/test_group.py

@@ -1641,10 +1641,12 @@ async def test_create_hierarchy_existing_nodes(
     elif impl == "async":
         with pytest.raises(err_cls, match=re.escape(msg)):
             tuple(
-                x
-                async for x in create_hierarchy(
-                    store=store, nodes={"node": new_metadata}, overwrite=False
-                )
+                [
+                    x
+                    async for x in create_hierarchy(
+                        store=store, nodes={"node": new_metadata}, overwrite=False
+                    )
+                ]
             )
     else:
         raise ValueError(f"Invalid impl: {impl}")