Don't build empty nested records
Don't build empty nested records

If there are no records, administrator can just use the "add" button.
Creating empty records could lead to accidental changes when we edit an
existing record.

This commit reverts some of the changes done in 4030daf. In that commit,
no reason was specified for those changes.

AyuntamientoMadrid/transparencia,AyuntamientoMadrid/transparencia,AyuntamientoMadrid/transparencia,AyuntamientoMadrid/transparencia