editor: Revert flattening of code actions in mouse context menu (#28988)

In light of making context not move dynamically, reverting back these
changes.

- Doing it async will lead to a loading state, which moves the context
menu.
- Doing it sync introduces noticeable lag in opening the context menu.
   
Future idea is to introduce fixed code actions like refactor, rewrite,
etc depending on code action kind [(see
more)](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#codeActionKind)
which will use submenus.
 
Release Notes:

- N/A

crates/collab/src/tests/editor_tests.rs

@@ -694,15 +694,7 @@ async fn test_collaborating_with_code_actions(
     // Confirming the code action will trigger a resolve request.
     let confirm_action = editor_b
         .update_in(cx_b, |editor, window, cx| {
-            Editor::confirm_code_action(
-                editor,
-                &ConfirmCodeAction {
-                    item_ix: Some(0),
-                    from_mouse_context_menu: false,
-                },
-                window,
-                cx,
-            )
+            Editor::confirm_code_action(editor, &ConfirmCodeAction { item_ix: Some(0) }, window, cx)
         })
         .unwrap();
     fake_language_server.set_request_handler::<lsp::request::CodeActionResolveRequest, _, _>(