hydra-api: hidden -> visible

Dependencies

• [2] LX326CB7 Add hydra OpenAPI description (#750)
• [3] X7P27PO3 Return HTTP 400 when creating Project with nonexistent user
• [4] SGO33PVL hydra-api: add missing properties to PUT /project/{id}

Change contents

• replacement in hydra-api.yaml at line 178
  [2.5090]→[2.5090:5114](∅→∅)
  − hidden:
  [2.5090]

  [2.5114]
  + visible: