Backport: Avoid redirect loop from archived pages [v16.11]

What does this MR do and why?

Same as !5370 (merged), but for 16.11.

We fixed this for recent 17.x versions, but 16.11 will be on the versions dropdown for another year, so let's fix this one as well.

Related: gitlab-org/technical-writing/docs-gitlab-com#278 (closed).

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Closes #404 (moved)