Migrate to new Top Level Group

A new GitLab TLG has been created, to promote open source software that was created by the wider GitLab security org.

• New cis group path: https://gitlab.com/gitlab-security-oss/cis
• Old cis group path: https://gitlab.com/gitlab-org/software-supply-chain-security/compliance/engineering/cis

This issue is to document the changes required to migrate.