Attributes can be dragged to the Property list in the Blackboard when reordering entries

Steps to reproduce:

1. Create a new URP 3D Project and install the Visual Effect Graph Package
2. Create a new Visual Effect Graph Asset in the Project Browser and open it
3. Enable the Blackboard and add any Attribute and a Property
4. Drag either Built-in or Custom Attributes to the top of the Property List

Actual results: Attributes can be reordered together with Properties, their position is not saved and they are returned back to the Attributes list when the Blackboard updates

Expected results: Attributes cannot be dragged to the top of the Property list

Reproducible with versions: 6000.0.14f1, 6000.0.76f1, 6000.3.17f1, 6000.4.10f1, 6000.5.0b11, 6000.6.0a6

Not reproducible with versions: 6000.0.13f1

Tested on (OS): Windows 11