Remove model_contract from artifact_path

[gabegma]

Description:

• model-contract was not in the right config scope. It was there for the artifact_path, but as we discussed, we should not include anything that is not related to the dataset in the artifact_path.

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[JosephMarinier]

Wow! So model_contract goes in ModelContractConfig 🤯 Who would have thought? 😝 Thank you for fixing this!