CEO shadow relaunch

Things to do:

1. Get schedule merged: gitlab-com/content-sites/handbook!1376 (merged)
2. Draft comms for posting in Slack, Stella to review
3. Update CEO shadow handbook page, removing anything out of date | gitlab-com/content-sites/handbook!1515 (merged)
4. Update on/off-boarding templates | https://gitlab.com/gitlab-com/ceo-shadow/onboarding/-/merge_requests/62
5. Clean up projects in subgroup
   • Related AR: https://gitlab.com/gitlab-com/team-member-epics/access-requests/-/issues/25859