Merge branch 'nh/check-if-tool-versions-exists' into 'main'

Move Ruby path update to script and improve .tool-versions check

See merge request https://gitlab.com/gitlab-org/gitlab-development-kit/-/merge_requests/3570



Merged-by: Ash McKenzie <amckenzie@gitlab.com>
Approved-by: Ash McKenzie <amckenzie@gitlab.com>
Co-authored-by: Nao Hashizume <nhashizume@gitlab.com>