UI: Remove "service type" from auto-config stream page

The "Custom" service has been moved, and is now an item called "Custom"
in the "Services" combo box.  This simplifies the stream page of
auto-configuration and removes an unnecessary widget.  Overall a minor
but nice slimline/improvement on user experience.

UI/window-basic-auto-config.hpp

@@ -160,6 +160,7 @@ class AutoConfigStreamPage : public QWizardPage {
 	bool ready = false;
 
 	void LoadServices(bool showAll);
+	inline bool IsCustom() const;
 
 public:
 	AutoConfigStreamPage(QWidget *parent = nullptr);