### Tested versions

- Reproducible in: v4.2.stable.arch_linux
- Not Reproducible in: v4.1.3.stable.official [f06b6836a]

### System information

Garuda Linux (2.6.19-2)

### Issue description

A minor issue where UI Icons are not rendering on the Group Editor window, attaching a screenshot for reference:
![Screenshot_604](https://github.com/godotengine/godot/assets/22623256/c366164a-3d9a-4dcf-97a0-199b5a5a7ecc)

The icons were expected for Buttons like Add, Remove, Filter, etc.

### Steps to reproduce

Select any Node and go to the `Node` panel, click `Manage Groups` and the window will open.

### Minimal reproduction project (MRP)

Minor issue, easily reproducible following the above steps.
item->set_editable(0, true);
		if (can_be_deleted) {
			item->add_button(0, get_editor_theme_icon(SNAME("Remove")), DELETE_GROUP);
			item->add_button(0, get_editor_theme_icon(SNAME("ActionCopy")), COPY_GROUP);
		} else {
			item->set_selectable(0, false);
		}
	}
}
void GroupsEditor::set_current(Node *p_node) {
	node = p_node;
	update_tree();
}
void GroupsEditor::_show_group_dialog() {
	group_dialog->edit();
}
void GroupsEditor::_bind_methods() {
	ClassDB::bind_method("update_tree", &GroupsEditor::update_tree);
	ClassDB::bind_method("_group_selected", &GroupsEditor::_group_selected);
}
GroupsEditor::GroupsEditor() {
	node = nullptr;
	VBoxContainer *vbc = this;
	group_dialog = memnew(GroupDialog);
	add_child(group_dialog);
	group_dialog->connect("group_edited", callable_mp(this, &GroupsEditor::update_tree));
	Button *group_dialog_button = memnew(Button);
	group_dialog_button->set_text(TTR("Manage Groups"));
	vbc->add_child(group_dialog_button);
	group_dialog_button->connect("pressed", callable_mp(this, &GroupsEditor::_show_group_dialog));