Release QA: verify the images being tested match the Image description file

During the 7.1 release process, the IDF (wiki/src/install/v2/Tails/amd64/stable/latest.json) was not updated (well, it was, but for whatever reason this commit was later removed from the release branch). Let's make sure we don't release in that state.

The process I'm re-adding here was salvaged from 5245f05d, and adjusted to better fit this slightly different context.

refs #21272