- Changed the default AUTO_DEVOPS_POSTGRES_CHANNEL to 2. This will
  result in deployments failing for users still on channel 1, with
  instructions on how to stay on channel 1 or move to channel 2.

- Moved the default value for POSTGRES_VERSION out of
  Auto-DevOps.gitlab-ci.yml into auto-deploy-image and
  Test.gitlab-ci.yml to give auto-deploy-image the flexibility to set a
  different default version depending on the value of
  AUTO_DEVOPS_POSTGRES_CHANNEL

See https://gitlab.com/gitlab-org/cluster-integration/auto-deploy-image/-/compare/v0.14.0...v0.15.0