hydrate-cluster and bootstrap systemd vault policy format drift

Since commit https://github.com/input-output-hk/bitte/commit/81a576eab9ae0653a5b9ee706f6ba36a10c00932, anytime the bootstrap core node is deployed with a change and then a TF hydrate-cluster plan is performed afterwards there will be at least a minimal no-op TF plan diff due to bootstrap script declaring vault policies in hcl format and hydrate-cluster declaring vault policies in json. Bringing the syntax to the same format for both methods should resolve -- likely the preference is to bring the bootstrap scripts to use json.

Start with the bootstrap scripts and the hydrate-cluster Terraform configuration, using commit 81a576eab9ae0653a5b9ee706f6ba36a10c00932 as context. Compare how each declares Vault policies, align the policy format, and verify that deploying the bootstrap core node followed by a hydrate-cluster plan produces no policy-format diff.

Written by the indexing model from the issue text.