Codefix: [UI] Incorrect initialisation order for rail/road toolbars. (#12843)

The toolbar state was set after the widget tree is created, during which toolbar state is needed.

src/rail_gui.cpp

@@ -438,8 +438,9 @@ struct BuildRailToolbarWindow : Window {
 
 	BuildRailToolbarWindow(WindowDesc &desc, RailType railtype) : Window(desc)
 	{
-		this->InitNested(TRANSPORT_RAIL);
+		this->CreateNestedTree();
 		this->SetupRailToolbar(railtype);
+		this->FinishInitNested(TRANSPORT_RAIL);
 		this->DisableWidget(WID_RAT_REMOVE);
 		this->OnInvalidateData();
 		this->last_user_action = INVALID_WID_RAT;

src/road_gui.cpp

@@ -349,8 +349,9 @@ struct BuildRoadToolbarWindow : Window {
 	BuildRoadToolbarWindow(WindowDesc &desc, WindowNumber window_number) : Window(desc)
 	{
 		this->Initialize(_cur_roadtype);
-		this->InitNested(window_number);
+		this->CreateNestedTree();
 		this->SetupRoadToolbar();
+		this->FinishInitNested(window_number);
 		this->SetWidgetDisabledState(WID_ROT_REMOVE, true);
 
 		if (RoadTypeIsRoad(this->roadtype)) {