Make projects table smaller and migrate fields to project_settings

I'm creating this issue to create awareness of gitlab-org/gitlab#19826 (closed)

I see quite regularly MRs are adding more fields to the projects table (for example gitlab-org/gitlab!18408 (merged)), so it would be nice if someone of the database team to work on migrating field to a separate projects_settings table.

Or maybe we should start creating the table, and have at least new MRs trying to add fields to projects add the fields to project_settings instead of projects, so we stop creating more ~"technical debt".