Technical controls protect the build pipeline from tampering and enforce security gates at each stage
The technical facet locks down the pipeline so build definitions, secrets and deployment steps cannot be tampered with, enforcing a security gate at each stage.
The CI/CD hardening technical facet locks down build definitions, secrets and deployment steps against tampering, a practical mechanism for the source code access control A.8.4 requires.
Locking the pipeline down so build definitions and deployment steps cannot be tampered with is A.8.9's configuration integrity applied to the delivery system.