Make dscc_number factory slimmer
Make dscc_number factory slimmer

Although it could potentially be used to create
an invalid object, the trait should do what it
says on the tin. I think it predated the 
`:opened` trait, it doesn't seem to need the
extra attributes any more.
ministryofjustice/defence-request-service,ministryofjustice/defence-request-service,ministryofjustice/defence-request-service,ministryofjustice/defence-request-service