While the API still has a column and field for personalisation I think
it makes sense for it to consider the personalisation when serialising
the broadcast, so we should have a test for this.
This way the API still works as a coherent whole, and the admin app just
happens to be a client of the API which doesn’t implement the
personalisation feature.
If we want to remove personalisation from the API at another time we
should do it wholesale.