curl --request GET \
  --url http://localhost:8080/cabinet/admin/users/{user_id}/available-tariffs

{
  "user_id": 123,
  "promo_group_id": 123,
  "promo_group_name": "<string>",
  "tariffs": [],
  "total": 0,
  "current_tariff_id": 123,
  "current_tariff_name": "<string>"
}