Mark all links on the website which should use the mirror pool

All links to the ISO image and signatures, as well as other files which should be downloaded from a mirror, would need to use the CSS class “use-mirror-pool”, so their URL prefix will be randomly modified.

Feature Branch: feature/11329-use-mirror-pool

Parent Task: #7161 (closed)

Related issues

Blocks #8642 (closed)

Original created by @u on 11329 (Redmine)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information