Backport 16.1 | Don't 500 when pages tries to serve a chunked file

What does this MR do and why?

Describe in detail what merge request is being backported and why

Backport !7006 (merged) to 16.1. The fix does not need 16.0 and 15.11 backports, as the bug is based on the NGINX bump merged into 16.1.

Related issues

Closes gitlab#416803 (closed)

Closes gitlab#415934 (closed)

Relates gitlab#416258 (closed)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• This MR is backporting a bug fix, documentation update, or spec fix, previously merged in the default branch.
• The original MR has been deployed to GitLab.com (not applicable for documentation or spec changes).
• This MR has a severity label assigned (if applicable).

Note to the merge request author and maintainer

The process of backporting bug fixes into stable branches is tracked as part of an internal pilot. If you have questions about this process, please:

• Refer to the internal pilot issue for feedback or questions.
• Refer to the patch release runbook for engineers and maintainers for guidance.