Add a command to migrate old job business models to licensed

[Alberto Vilches (avilches)]

Summary

Adds migrate_job_business_model, the management command that rewrites the old SUBSIDIZED business model of existing jobs to LICENSED. It runs from the internal deployment repo as a Kubernetes Job through the existing qiskit-serverless-migrations chart, the same way the earlier migrate_old_job_* commands do.

Set as draft because it needs the LICENSED field from #2427, so it targets that branch instead of main until it merges.

Details and comments

--dry-run only reports how many rows still hold SUBSIDIZED, without writing. Safe to interrupt and rerun, since each run only touches rows that still hold the old name.

Once every job row is migrated, a follow-up cleanup PR removes core/domain/subsidized_license_mapping.py and its two call sites, drops SUBSIDIZED from BusinessModel, and turns BILLING_NAMES back into an identity map.

[Tova Roth (riley2012)]

LGTM!