Cache backward compatibility with 2.15.0
...for datasets without scripts

It takes into account the changes in cache from
- https://github.com/huggingface/datasets/pull/6493: switch to `config/version/commit_sha` schema
- https://github.com/huggingface/datasets/pull/6454: fix `DataFilesDict` keys ordering when hashing

requires https://github.com/huggingface/datasets/pull/6493 to be merged