Switching between UI Documents with different Canvas sizes marks the UXML file as dirty

Steps to reproduce:

1. Open the attached project
2. Open the 'Test.uxml' asset
3. Observe that the Canvas size is set to Match Game View (1920x1080)
4. Open 'Test 1.uxml' asset
5. Observe that the Canvas size is set to (350x450)
6. Start switching between Test and Test1 assets

Actual results: After a UI document with a different Canvas Size is opened, it is marked as Dirty regardless of whether any changes were made

Expected results: Switching between UI Documents should not mark them as dirty if the User does not make changes to the assets

Reproducible with versions: 6000.0.41f1, 6000.0.50f1, 6000.1.4f1, 6000.2.0b3

Not reproducible with versions: 2022.3.62f1, 6000.0.40f1

Tested on (OS): macOS 15.5