collab_ui: Remove dependency on vcs_menu (#21016)

This PR removes the `vcs_menu` dependency from `collab_ui`.

We were only depending on this to call `vcs_menu::init`, which isn't
necessary to do here.

Release Notes:

- N/A

crates/zed/src/main.rs

@@ -462,6 +462,7 @@ fn main() {
         call::init(app_state.client.clone(), app_state.user_store.clone(), cx);
         notifications::init(app_state.client.clone(), app_state.user_store.clone(), cx);
         collab_ui::init(&app_state, cx);
+        vcs_menu::init(cx);
         feedback::init(cx);
         markdown_preview::init(cx);
         welcome::init(cx);