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/copilot/src/copilot.rs

@@ -971,7 +971,7 @@ async fn clear_copilot_dir() {
 }
 
 async fn get_copilot_lsp(http: Arc<dyn HttpClient>) -> anyhow::Result<PathBuf> {
-    const SERVER_PATH: &'static str = "dist/agent.js";
+    const SERVER_PATH: &str = "dist/agent.js";
 
     ///Check for the latest copilot language server and download it if we haven't already
     async fn fetch_latest(http: Arc<dyn HttpClient>) -> anyhow::Result<PathBuf> {