Portals - fix duplication of instanced scenes during conversion
Portals - fix duplication of instanced scenes during conversion

During room conversion, if a prefixed Spatial is converted to a Room / RoomGroup etc, when using instanced scenes the owner was incorrectly set, resulting in the instanced scene objects being duplicated.

This PR corrects this.

ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot,ex/godot