Merge branch 'leipert-remove-minor-legacy-nav-code-paths' into 'master'

Remove legacy code path from new namespace page

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/137429



Merged-by: Illya Klymov <xanf@xanf.me>
Approved-by: Illya Klymov <xanf@xanf.me>
Approved-by: Scott de Jonge <sdejonge@gitlab.com>
Reviewed-by: Scott de Jonge <sdejonge@gitlab.com>
Co-authored-by: Lukas Eipert <leipert@gitlab.com>