This commit prevents considering Scenes (and a few other ID types, like
WindowManager or Library) as being part of liboverride hierarchies.
Having collections, objects, obdata etc. depend on a Scene ID is
typically not considered as a valid setup for linked data.
And in any case, Scenes are not officially supported for liboverrides
currently.
In the case of #121410, where a driver of the armature object was using
the Scene ID, it will simply keep that scene reference pointing to the
linked scene, instead of overriding the whole scene.
e30893e3c2