Reducing `target_feature` check-cfg merge conflicts
It was rightfully pointed in https://github.com/rust-lang/rust/pull/133099#discussion_r1862490542 that the expected values for the `target_feature` cfg are regularly updated and unfortunately the check-cfg tests for it are very merge-conflict prone.
This PR aims at drastically reducing the likely-hood of those, by normalizing the "and X more" diagnostic, as well as making the full expected list multi-line instead of being on a single one.
cc `@RalfJung`
r? `@jieyouxu`
8a26a8bf48