chore: Fix some violations of 'needless_pass_by_ref_mut' lint (#18795)

While this lint is allow-by-default, it seems pretty useful to get rid
of mutable borrows when they're not needed.

Closes #ISSUE

Release Notes:

- N/A

crates/zed/src/reliability.rs

@@ -347,7 +347,7 @@ pub fn monitor_main_thread_hangs(
 fn upload_panics_and_crashes(
     http: Arc<HttpClientWithUrl>,
     installation_id: Option<String>,
-    cx: &mut AppContext,
+    cx: &AppContext,
 ) {
     let telemetry_settings = *client::TelemetrySettings::get_global(cx);
     cx.background_executor()