Migration for updating parent_tag for 'housing' detailed guides

The housing tag is being replaced with housing-local-services, this updates the detailed guides.

This should be merged and deployed after this Panaopticon PR - https://github.com/alphagov/panopticon/pull/222.

The browse category slugs are redirceted in this router-data PR - https://github.gds/gds/router-data/pull/198.