Use const over static for string literals (#18635)

I noticed a few places where we were storing `&'static str`s in
`static`s instead of `const`s.

This PR updates them to use `const`.

Release Notes:

- N/A

crates/zed/src/reliability.rs

@@ -441,7 +441,7 @@ async fn upload_previous_panics(
     Ok::<_, anyhow::Error>(most_recent_panic)
 }
 
-static LAST_CRASH_UPLOADED: &str = "LAST_CRASH_UPLOADED";
+const LAST_CRASH_UPLOADED: &str = "LAST_CRASH_UPLOADED";
 
 /// upload crashes from apple's diagnostic reports to our server.
 /// (only if telemetry is enabled)