Release with tagged images for Auto Build

Similar to how we release tagged versions of auto-deploy, do the same for auto build.

Problem to solve

Auto build currently uses master:stable image

We have two regressions recently which meant all users of Auto-DevOps were affected.

Proposal

  1. Create versioned image tags similar to https://gitlab.com/gitlab-org/cluster-integration/auto-deploy-image
  2. Stop pushing new images under master:stable.
  3. Update Jobs/Build.gitlab-ci.yml to use versioned docker images

/cc @proglottis @hfyngvason @DylanGriffith

Edited by Thong Kuah