`relative_url_root` is manifesting as a query param

[joescottdave]

Issue

When performing a search we are seeing urls like so: https://hmlr-dev-pres.epimorphics.net/app/ppd/search?relative_url_root=%2Fapp%2Fppd

Steps to reproduce

Search in ppd explorer using a postcode, see that the resulting url as the query parameter relative_url_root