Updates required to use with DDEV

[AlanJIsaacson]

When adding DDEV to a project, it means we need to remove DB settings from wp-config-development which means we cannot run MAMP and DDEV side-by-side.

Do we need to update multi-env-config to help deal with this?

Currently has issues establishing a DB connection
https://github.com/ukparliament/Education-Microsite/tree/feature/adding-ddev