Fix ordering of imported but unchanged projects
What does this MR do?
Fixes ordering of projects imported from GitHub (or other) but that have not seen local modification. These projects are created with last_activity_at set to NULL, causing them to always float to the top of the projects list.
It also corrects records in the database with this value missing by setting them to the value of updated_at.
Are there points in the code the reviewer needs to double check?
Not since the second commit where I've mirrored what's done in app/services/projects/create_service.rb:86 to set this value.
Why was this MR needed?
Well the sorting was wrong, so yeah.