fix: validate subject field in manifest database not blob storage

mentioned in commit a538eb0e

mentioned in issue #1641 (closed)

mentioned in merge request gitlab-org/build/CNG!2517 (closed)

mentioned in merge request gitlab-org/charts/gitlab!4412 (merged)

mentioned in merge request omnibus-gitlab!8578 (merged)

mentioned in merge request gitlab-org/build/CNG!2519 (closed)

mentioned in merge request gitlab-com/gl-infra/k8s-workloads/gitlab-com!4589 (merged)

mentioned in merge request gitlab-com/gl-infra/k8s-workloads/gitlab-com!4596 (merged)

mentioned in merge request gitlab-com/gl-infra/k8s-workloads/gitlab-com!4597 (merged)

mentioned in merge request gitlab-development-kit!5048 (merged)