Instancing regression in runtimeloader example

To reproduce: start the runtimeloader example, and open ReciprocatingSaw.gltf from the glTF-Sample-Models repository. Press the Instancing button. With Qt 6.3.1 the imported scene is instanced as a whole. With Qt 6.4.2 (and the dev branch), the individual components are instanced at different positions.

This is a regression in Qt, and not in the example, since it can be reproduced by running 'qmlscene --core-profile' on main.qml from 6.3.1