Merge branch 'tmccaslin-retention-changes' into 'master'

AI Docs: Update Anthropic and GitLab retention info

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/142366



Merged-by: Suzanne Selhorn <sselhorn@gitlab.com>
Approved-by: Kevin Chu <kchu@gitlab.com>
Co-authored-by: Taylor McCaslin <tmccaslin@gitlab.com>