Integrate USB image in the release process

Review & rubber-duck: kibi (3h)

This includes at least:

• adjust manual test suite
• what about UDFs? the full upgrade path only includes the ISO it’s not used anyway so we don’t care, see details in 2d7cf8ac4308e290c4a3872fd80fd60b5e6ed459
• upload to iso-archive
• upload to rsync server
• 2 torrent files
• wiki/src/inc/* as requested by doc writers, see #16163 (closed)
• IDF:
  • adapt IDF generation
  • git grep install/v1
  • coordinate v1 vs. v2 IDF generation (both for some time?) with the release of the updated Verification Extension + the Installation Assistant version check for that extension
• probably more stuff that we’ll discover along the way

Feature Branch: doc/15999-integrate-usb-image-in-the-release-process

Parent Task: #15292 (closed)

Subtasks

• #16164 (closed)
• #16171 (closed)

Related issues

• Blocked by #16163 (closed)
• Blocked by #16112 (closed)

Original created by @u on 15999 (Redmine)