- The assets cache image is built against the merge commit (aka
  `$CI_COMMIT_SHA`): https://gitlab.com/gitlab-org/gitlab/-/blob/db839bf23e216b43e8b920265d7dc814a9365cc9/.gitlab/ci/frontend.gitlab-ci.yml#L58-63
- The CNG images are built against the branch: https://gitlab.com/gitlab-org/gitlab/-/blob/db839bf23e216b43e8b920265d7dc814a9365cc9/scripts/trigger-build#L181
- The problem is that the branch `HEAD` commit isn't the same as the
  merge commit, thus assets in the assets image have a high chance of
  having a different hash than the actual assets that would be
  generated from the branch `HEAD`.
- The correct assets are the ones generated from the merge commit, so
  we're changing the CNG trigger variables to pass
  `GITLAB_VERSION=$CI_COMMIT_SHA` instead of
  `GITLAB_VERSION=$CI_COMMIT_REF_NAME` so that the components are
  built from the same commit as the assets image.
Signed-off-by: Rémy Coutable <remy@rymai.me>