Remove MigrateLegacyStorageToDeploymentService

Remove

• https://gitlab.com/gitlab-org/gitlab/blob/50d70ae5a15581c911d164ef2a93b98c0b1bfbf8/app/services/pages/migrate_legacy_storage_to_deployment_service.rb#L4
• https://gitlab.com/gitlab-org/gitlab/blob/50d70ae5a15581c911d164ef2a93b98c0b1bfbf8/app/services/pages/zip_directory_service.rb#L4
• tests for these services