Fix: Apply widget's internal padding to scrollbar capacity/position. (#12801)

For non-WWT_MATRIX widgets, scrollbars need to take account of the internal padding used for the widget.

This is not normally noticeable as framerect padding is only 2 extra pixels

src/town_gui.cpp

@@ -996,7 +996,7 @@ public:
 
 	void OnResize() override
 	{
-		this->vscroll->SetCapacityFromWidget(this, WID_TD_LIST);
+		this->vscroll->SetCapacityFromWidget(this, WID_TD_LIST, WidgetDimensions::scaled.framerect.Vertical());
 	}
 
 	void OnEditboxChanged(WidgetID wid) override