Ignore big datasets from external files
Raise an error for big datasets that use a loading script to download data files external to HF.

It was the only case left for a big dataset to not be ignored. Hopefully it makes the `/parquet-and-dataset-info` job stop wasting too much resources on big datasets.

Close https://github.com/huggingface/datasets-server/issues/806
Ignore big datasets from external files: Raise an error for big datasets that use a loading script to download data files external to HF.

It was the only case left for a big dataset to not be ignored. Hopefully it makes the `/parquet-and-dataset-info` job stop wasting too much resources on big datasets.

Close https://github.com/huggingface/datasets-server/issues/806