Update undo redo allowed after switching scene tab

It has different status in different tabs.

editor/editor_node.cpp

@@ -3832,6 +3832,8 @@ void EditorNode::_set_current_scene_nocheck(int p_idx) {
 	if (tabs_to_close.is_empty()) {
 		callable_mp(this, &EditorNode::_set_main_scene_state).call_deferred(state, get_edited_scene()); // Do after everything else is done setting up.
 	}
+
+	_update_undo_redo_allowed();
 }
 
 void EditorNode::setup_color_picker(ColorPicker *p_picker) {