docs: deprecations and removals on CI_BUILD_* are too vague
Some deprecated pre-defined variables in GitLab CI 9.0 are still available even on CI 12.6.
https://docs.gitlab.com/ee/ci/variables/deprecated_variables.html is not a good list to check deprecated variables (in 9.0)
😄As showed in diffs of !21782 (merged), we can still use
CI_BUILD_IDwith GitLab CE/EE/Runner 12.5 or 12.6-pre.
You can see the following variables at !21782 (diffs) (or https://gitlab.com/tnir-pick-mr-test/ci-debug-trace/-/jobs/379424655 (member-only so membership can be requested if needed))
deprecated but still available pre-defined variables
deprecated and removed pre-defined variables
pre-defined variables needed to be investigated