Rollup merge of #128398 - awilfox:awilfox/fix-tidy-quote, r=jieyouxu

tidy: Fix quote in error message

I noticed that the backticks around the error code wasn't done properly in this string when I was building Rust 1.80.0 and found it is still this way in nightly.  Example:

```
warning: Error code `E0595` needs to have at least one UI test in the `tests/error-codes/` directory`!
warning: Error code E0602`` has a UI test file, but doesn't contain its own error code!
warning: Error code `E0619` needs to have at least one UI test in the `tests/error-codes/` directory`!
```

This commit fixes it to match the other warning strings.

Author: matthiaskrgr