Delete artefacts when changed to nonindexed kinds
Delete artefacts when changed to nonindexed kinds

We have had some artefacts created (incorrectly) as Answers when they should
have been CompletedTransactions. These were not removed automatically. This
change would ensure that they are in future.

theodi/panopticon,theodi/panopticon,alphagov/panopticon,theodi/panopticon,alphagov/panopticon,alphagov/panopticon,theodi/panopticon,alphagov/panopticon