Fix MenuBar min size not updating after child rename

[timothyqiu]

To reproduce the issue:

1. Create a MenuBar.
2. Add a PopupMenu child for it.
3. Rename the PopupMenu node so the button text is shorter on the menu bar.
4. Try to resize the menu bar: you can't make it narrower than its original width.
5. Switch to another scene and then back: now you can shrink the menu bar.

[bruvzg]

Both queue_redraw and update_minimum_size probably should be called after the loop, and can be wrapped in if (!is_global) { ... } since neither is relevant for macOS global menu.

[Repiteo]

Thanks!