Removed unnecessary &String -> &str, now that &String implements StableOrd as well
Applied a few nits suggested by lcnr to PR #110040 (nits can be found [here](https://github.com/rust-lang/rust/pull/110040#pullrequestreview-1469452191).)
Making a new PR because the old one was already merged, and given that this just applies changes that were already suggested, reviewing it should be fairly open-and-shut.
a5561eb4d5