Wire in release-tools for staging-ref environment

Part of immediate short term plan in gitlab-org&6401 (closed)

Wire in release-tools also related to delivery#1427 and other works from &361

Exit criteria:

• Decide on the right point in the release-tools pipeline to add the deployment task
• Explore how to sync stg-cny deployment to staging-ref - https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/14046#note_691537563
• Coordinated pipelines trigger the staging-ref deployment in parallel to stg-cny deployments
• Staging-ref deployment success or failure is reported in the #qa-staging-ref channel

Please make sure release managers are aware of when this change will be merged in.