Migration for updating become-a-driving-instructor owning app and slug

become-a-driving-instructor is currently a smart-answer. It is being replaced with a simple smart-answer. This migration changes the owning app, kind and rendering app before changing the slug.

There are some other things that need to happen before this is deployed.

The new simple-smart-answer needs to be published.
The existing slug needs to be deleted in search.
The smart-answer needs to be deleted (https://github.com/alphagov/smart-answers/pull/1042)