So now we test in depth at the model level, and can be a bit more
relaxed about integration tests for translations.
Note we're defining some extra factories to make sure all translatable
attributes with presence validation rules are mandatory. This way we can
simplify the way we obtain required fields, using `required_attribute?`.
Otherwise, fields having an `unless` condition in their presence
validation rules would count as mandatory even when they're not.
Having translations makes this validation too complex and not worth the
effort, since now we can't just scope in a single column but we need to
scope in the translations locale and the question ID.
