Backup and Restore procedure

[mitch-lbw]

• Setup backup procedure according to https://github.com/bitnami/charts/tree/main/bitnami/postgresql#backup-parameters
  • we need a backup directory pointing to a managed storage box
  • expected output format is <database_name>.tar
  • we need to check if this does rolling backups and how the naming is done then - expectation is, that <database_name>.tar is always the newest backup
• Test restore using adapted script
  • an additional env BACKUP_DIRECTORY is needed, which points to the backup directory used by the bitnami backup procedure