So swh-search can use a Kafka client to fill its DB with metadata.
- It adds a new Kafka topic, of objects that are not part of the data model
- Only this idx-storage endpoint writes to Kafka (because I don't think we need the other ones) -> inconsistency
Depends on D1958
^ implementation detail (some tests are currently failing in that diff because of data validation issue which are being fixed in this 1958)