Content-Type in response header is incorrect on resources in Wiki page

Summary

After migration from 11.4.5 to 11.5.0-ee (cb71fca3) the content-type of files stored in the wiki project always return text/plain regardless of the extension/mime

Steps to reproduce

Upload an html page, css and js into the wiki project and access it via the browser.

Example Project

https://gitlab.com/LeandroPT/testwiki.git

Go to the wiki and press the link available

the page opens like this: image

using a tool like "Requestly" and changing the response Header Content Type to the correct type the page renders properly image

What is the current bug behavior?

Content-Type response header for wiki raw file content is incorrect for html, css, js files.

The previous version had the problem described in #26390 (moved) that is no longer an issue in this release.

What is the expected correct behavior?

The correct Content-Type header according to the extension

Output of checks

This bug happens on GitLab.com

Edited by Leandro Teixeira