iOS: Move updateAutomaticKitList() trigger closer to its user

This removes the IosPlugin::kitsRestored() member that does not
fully fit the standard plugin implementation pattern.

Change-Id: Iedd79e5326b85b189673c19e1920e21c34cd03bb
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/ios/iosplugin.h

@@ -43,8 +43,6 @@ private:
     bool initialize(const QStringList &arguments, QString *errorMessage) final;
     void extensionsInitialized() final {}
 
-    void kitsRestored();
-
     class IosPluginPrivate *d = nullptr;
 };