wizard: feature request - add dataset.non_redistributable: true as default to private steps

[spoonerf]

One-liner

Let's make it a bit simpler to ensure private datasets are non-redistributable.

Context & details

Currently, I believe there are three things you need to do to ensure a dataset is non-redistributable in the ETL:

• In the Snapshot .dvc have is_public: false
• Use data-private and snapshot-private in the dag
• Set the dataset metadata as non_redistributable: true, typically in garden

The first two are done automatically in Wizard when you select that the dataset is private. I think it would make sense to also make the third one automatic, unless there is some complication I'm not thinking of?