add dummy value for region in backup

related to sylva-projects/sylva-core#4713 (closed)

explanation in sylva-projects/sylva-core#4713 (comment 3917258004)

observed in

• https://gitlab.com/sylva-projects/sylva-core/-/jobs/16765266901
• deploy-management-cluster (#16772223483) · Jobs · Sylva-projects / sylva-core · GitLab