Revert "Merge branch 'tbulva-duo-rail-old-layout' into 'master'"

What does this MR do and why?

Relates to the original issue: https://gitlab.com/gitlab-org/gitlab/-/issues/570523+s

Reverting this because it uses mocked values for the custom-models selectors. Details: https://gitlab.slack.com/archives/C06D5C70MD2/p1758317437115209

Revert "Merge branch 'tbulva-duo-rail-old-layout' into 'master'"

This reverts merge request !204655 (merged)