Graph Toolkit window becomes dirty when entering Play Mode when there are any number of variables in the blackboard

Steps to reproduce:

1. Open the attached "GTK_menuBug.zip" project
2. Open the "New Graph" asset in the Graph Toolkit Editor
3. Enable the Blackboard in the Graph Toolkit Editor
4. Enter Play Mode
5. Focus on the "New Graph" window
6. Observe the Graph window

Actual results: The window becomes dirty

Expected results: The window is not dirty

Reproducible with versions: 6000.5.0a9, 6000.5.0b4, 6000.6.0a3

Not reproducible with versions: 0.4.0-exp.2 (6000.3.0a6), 6000.4.3f1, 6000.5.0a8

Tested on (OS): Windows 11 Pro (25H2)

Notes:

• The variable doesn't have to be instantiated in the graph
• The window gets dirty every time Play Mode is entered
• This issue also occurs when the project is restarted, and when the graph assets are already opened