Ensure that site-org relationships always reflect organisation slugs
Ensure that site-org relationships always reflect organisation slugs

- When an organisation decides that it doesn't want a
  sub-organisation editing mappings anymore, we can remove the
  sub-organisation's slug from organisation_slugs in the YAML and the
  import will remove the relationship. That way, we don't have to
  manually delete the rows from the database.

alphagov/transition,alphagov/transition,alphagov/transition