refactor(tvix/castore/directorysvc): AsRef traverse_to

Change-Id: I641bd4ab3de591a013f03137f1e16295946315f3
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10579
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

tvix/glue/src/tvix_store_io.rs

@@ -92,8 +92,7 @@ where
         // with the root_node and sub_path, descend to the node requested.
         Ok(self.tokio_handle.block_on({
             async {
-                directoryservice::descend_to(self.directory_service.as_ref(), root_node, sub_path)
-                    .await
+                directoryservice::descend_to(&self.directory_service, root_node, sub_path).await
             }
         })?)
     }