UINAME in nodedefs does not work when namespace is used

Tried in MaterialX 1.38.8.

Steps to reproduce:
1 - Unzip and put the attached nodedefs file in your libraries.
2 - Start materiaX Graph Editor
3 - Press Tab to bring up list of nodes
4 - Select the "namespace_debug" group
5 - The node "nodedef_without_namespace" correctly uses the uiname string
6 - The node "test:ND_nodedef_with_namespace" does NOT use the uiname string.

The documentation for uiname in nodedefs specifically says:
"This is most useful when the defines a namespace, so the user doesn't need to see a full namespaced path for the node."
Which is the exact case it fails in this test.

[namespace_debug.zip](https://github.com/AcademySoftwareFoundation/MaterialX/files/14171020/namespace_debug.zip)

Please check also the video below. The video highlights 2 issues. This ticket is about the first part of the video.

https://github.com/user-attachments/assets/d578721c-c2da-4b2e-9e2b-b1f253f413fe

Start by loading namespace_debug.zip in the MaterialX Graph Editor and reproducing the Tab-list behavior for the namespaced nodedef. Trace how UINAME is handled for namespaced versus non-namespaced nodedefs; done means the namespaced node displays its uiname instead of the full namespaced path.

Written by the indexing model from the issue text.