Merge USB image generation into master

To simplify the work on our infra, let’s merge the USB image generation changes into master so all branches behave the same.

segfault has prepared a topic branch already but it needs a little bit more work:

• the most recent relevant work done on feature/15292-usb-image is not there yet
• some of the work done recently on feature/15292-usb-image was applied there in batch via non-atomic commits (at least daaf326952d41a1afede41f42ce7ac6f8c7d05a6) which will make our Git history hard to follow
• finally, feature/15292-usb-image must be rebased on top of that new branch so we don’t end up with duplicate commits

I’ll do this ASAP in order to merge this branch into master and unblock the CI work that starts tomorrow.

Feature Branch: feature/15292-generate-usb-image

Parent Task: #15293 (closed)

Original created by @intrigeri on 16154 (Redmine)