Cleanup: Suppress python console warning after previous commit

Introduced in ee2f2f00bd

Without the `register` function we get the following error in the
console when running blender:

Warning! '<path_to_blender>/scripts/startup/nodeitems_builtins.py'
has no register function, this is now a requirement for registerable
scripts

Pull Request: https://projects.blender.org/blender/blender/pulls/132091

scripts/startup/nodeitems_builtins.py

@@ -42,3 +42,11 @@ node_tree_group_type = {
     'TextureNodeTree': 'TextureNodeGroup',
     'GeometryNodeTree': 'GeometryNodeGroup',
 }
+
+
+def register():
+    pass
+
+
+def unregister():
+    pass