Investiate removing metadataList from the "Get all metadatas" endpoint

[petterroea]

Not doing it now in case it causes regressions, so we don't have bugs during the customer demo next week 🙃

The /api/MetadataType endpoint returns a list of metadata types. The metadataList endpoint on each entry is always empty. We should investigate whether or not we should remove this field, or populate it.