can we ship a file with development settings and ask people doing dev setup to require that? and if it's needed for CI, load it based on the CI config variable from one of the postconfig hooks?

This task is to do that. It will help with T240244 as well.

Things to do:

• Autocreate Talk:Main_Page so that Help Panel will work out of the box
• Static task / config suggester for SuggestedEdits (loaded if $wgGEDeveloperModeFrontend is set?)
• Define a Mentor service, and provide a static list (with User:Admin) if the Mentors page doesn't exist.