Redirect index

Why is this change being made?

This MR redirects /index/? to the same path minus the /index/? at the Cloudflare worker level instead of using a middleware (as proposed in gitlab-com/marketing/digital-experience/buyer-experience!2565 (closed)).

Also included a couple of small changes that will have no effect on the worker's current behavior.

❯ curl -s -o /dev/null -w "%{redirect_url}\n" https://redirect-index.about.gitlab-review.app/abc/def/index
https://redirect-index.about.gitlab-review.app/abc/def/

❯ curl -s -o /dev/null -w "%{redirect_url}\n" https://redirect-index.about.gitlab-review.app/abc/def/index/
https://redirect-index.about.gitlab-review.app/abc/def/

Related: gitlab-com/marketing/digital-experience/buyer-experience#2578 (closed)

Author Checklist

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