Cleanup job token authentication for artifacts download

What does this MR do and why?

related to https://gitlab.com/gitlab-org/gitlab/-/issues/223214 and https://gitlab.com/gitlab-org/gitlab/-/issues/349877

This MR cleans up the last remaining checks for the artifact downloads since it's a prerequisite for https://gitlab.com/gitlab-org/gitlab/-/issues/349877.

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