Backport PR #19637 on branch v7.2.x (DOC: Ignore another link blocked by provider) - #19639

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• Do the proposed changes actually accomplish desired goals?
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linkcheck now fails with https://iauarchive.eso.org/static/publications/stylemanual1989.pdf which is unrelated. That one is known to be flaky.