Merge branch 'pedropombeiro/update-implementation-plan' into 'master'

Update Runner token implementation plan

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/138051



Merged-by: Fiona Neill <fneill@gitlab.com>
Approved-by: Fiona Neill <fneill@gitlab.com>
Co-authored-by: Pedro Pombeiro <noreply@pedro.pombei.ro>