Plugin template: use _iid macro instead of "org.qt-project..."

Change-Id: Ib3a10681f65ee5317cd2813deae2322a81aa75c6
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

share/qtcreator/templates/wizards/projects/cpplibrary/lib.h

@@ -30,7 +30,7 @@ public:
 class %{CN} : public %{BaseClassName}
 {
     Q_OBJECT
-    Q_PLUGIN_METADATA(IID "org.qt-project.Qt.%{PluginInterface}" FILE "%{PluginJsonFile}")
+    Q_PLUGIN_METADATA(IID %{PluginInterface}_iid FILE "%{PluginJsonFile}")
 
 public:
     explicit %{CN}(QObject *parent = nullptr);