Use Instant not chrono for telemetry (#20756)

We occasionally see dates in the future appearing in our telemetry. One
hypothesis is that this is caused by a clock change while Zed is running
causing date math based on chrono to be incorrect.

Instant *should* be a more stable source of relative timestamps.

Release Notes:

- N/A

crates/collab/src/tests/test_server.rs

@@ -168,7 +168,7 @@ impl TestServer {
             client::init_settings(cx);
         });
 
-        let clock = Arc::new(FakeSystemClock::default());
+        let clock = Arc::new(FakeSystemClock::new());
         let http = FakeHttpClient::with_404_response();
         let user_id = if let Ok(Some(user)) = self.app_state.db.get_user_by_github_login(name).await
         {