Remove unneeded 'static lifetimes on &strs in constants (#8698)

This PR removes unneeded `'static` lifetimes on `&str`s stored in
`const` declarations.

This addresses some Clippy lints about
[`redundant_static_lifetimes`](https://rust-lang.github.io/rust-clippy/master/index.html#/redundant_static_lifetimes).

In item-level `const` declarations we can rely on lifetime elision and
use the default `'static` lifetime.

Note that associated constants still require an explicit `'static`
lifetime, as explained in
https://github.com/rust-lang/rust/issues/115010.

Release Notes:

- N/A

crates/ai/src/providers/open_ai.rs

@@ -6,4 +6,4 @@ pub use completion::*;
 pub use embedding::*;
 pub use model::OpenAiLanguageModel;
 
-pub const OPEN_AI_API_URL: &'static str = "https://api.openai.com/v1";
+pub const OPEN_AI_API_URL: &str = "https://api.openai.com/v1";