Delay quit until language servers are gracefully shut down

Co-Authored-By: Antonio Scandurra <me@as-cii.com>
Co-Authored-By: Nathan Sobo <nathan@zed.dev>

crates/language/src/tests.rs

@@ -409,7 +409,7 @@ fn test_autoindent_adjusts_lines_when_only_text_changes(cx: &mut MutableAppConte
 
 #[gpui::test]
 async fn test_diagnostics(mut cx: gpui::TestAppContext) {
-    let (language_server, mut fake) = lsp::LanguageServer::fake(&cx.background()).await;
+    let (language_server, mut fake) = lsp::LanguageServer::fake(cx.background()).await;
 
     let text = "
         fn a() { A }