Problem

• With CAM-11631 skipping the auth check when the process definition key data is missing was removed when historic instance permissions are enabled
• The process definition key is missing when the history data was produced with a Camunda BPM version prior to 7.3 (yes, seven-dot-three!)
• The change in CAM-11631 leads to a situation that less data is shown when historic instance permissions are enabled and there exist historic process instances without process definition key when migrating from 7.12 to 7.13

Solution

• Don't change the legacy behavior and skip the auth check when the process definition key data is missing
• Add migration test to ensure that authorization checks are skipped when process definition key is missing (this prevents confusions in the future)