Fix elided lifetime in associated const

[compiler-errors]

Fix an unelided lifetime in an associated const.

The old code was equivalent to:

impl<'a> RegistryConfig {
    /// File name of [`RegistryConfig`].
    const NAME: &'a str = "config.json";
}

and not &'static str, as it might be in a regular const item.

This "regressed" in rust-lang/rust#97313, which started allowing this behavior (inadvertently, as far as I can tell). It's not necessarily clear to me that this is sound (or at least, it's not something we intended to be able to express), but it's also preventing me from doing crater runs to investigate fallout of this issue (rust-lang/rust#114713 and rust-lang/rust#114716).

[rustbot]

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[epage]

@bors r+

While I didn't write this, I feel like I've been writing similar code thinking rustc finally just did what I wanted :(

[bors]

📌 Commit b4a26b0 has been approved by epage

It is now in the queue for this repository.

[bors]

⌛ Testing commit b4a26b0 with merge 3705df0...

[bors]

☀️ Test successful - checks-actions
Approved by: epage
Pushing 3705df0 to master...