In various previous commits all the remaining usages of this file were removed
(b1d7e8fcb1, b1d7e8fcb1, 2afd946ba, b43e2168e3). Now this file is finally
completely unused, which means we can remove it.
The main reason why we don't want this file is that it heavily relied on the
preprocessor and makes it hard to decentralize implementation details of
individual nodes.
Pull Request: https://projects.blender.org/blender/blender/pulls/132855
2f04f2184c