https://docs.gitlab.com/ee/ci/yaml/includes.html#re-using-a-before_script-template uses `before_script` at top level.

As of three months ago (https://gitlab.com/gitlab-org/gitlab/-/commit/9c8bb8144936c860e7ec9c06af7e17504acaaa40), this appears to be deprecated: https://docs.gitlab.com/ee/ci/yaml/#globally-defined-image-services-cache-before_script-after_script

The default keyword was created to avoid having `before_script` at the top level: https://gitlab.com/gitlab-org/gitlab-foss/-/issues/62732