DRAFT: daml - adjust preapproval fee

[meiersi-da]

PR for alignment purposes. Daml tests are passing.

It's not really no pre-approval fee, but rather a free base duration. This provides a simpler experience for creating a pre-approval as any party, while still allowing long-duration pre-approvals where required. I could see us offering a similar UX for directory entries.

The fetching of the OpenMiningRound is unfortunate, but doesn't seem a bigger obstacle here than it is in other places.

Pull Request Checklist

Cluster Testing

• If a cluster test is required, comment /cluster_test on this PR to request it, and ping someone with access to the DA-internal system to approve it.
• If a hard-migration test is required (from the latest release), comment /hdm_test on this PR to request it, and ping someone with access to the DA-internal system to approve it.

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[moritzkiefer-da]

nice thanks