EDC 0.15.0 data migration

With the new EDC version coming there's the need to apply a data/config migration to ensure that the connector will be able to recognize the entities created prior to this new version.

More info on: https://github.com/eclipse-edc/Connector/tree/910fb7260e49a0408b4d31a5df3000ac20c4f506/docs/developer/decision-records/2025-08-26-participant-context#migration