Instead of using `BKE_library_foreach_ID_link()` as a way to find
embedded IDs in a generic way, explicitly just get the embedded node
tree. That's the only animatable embeddable ID anyway. And calling
`BKE_library_foreach_ID_link()` can have some unwanted side-effects
(especially when the rebuilding happens while already using a similar
function to loop over IDs).
Pull Request: https://projects.blender.org/blender/blender/pulls/131807
c116ed473e