Add an e2e spec for an artist whose only album folder has no images of its
own, while the artist folder holds folder.jpg (plus unrelated images) and
ArtistArtPriority starts with folder.*. Before #5856, the album's parent was
promoted into the album paths, so the artist folder resolved to the library
root and the artist got no image. The spec fails if that promotion comes
back, and passes on current code.
Refs #5823