Default and Result encoding properties have blank dropdowns by default when opening the Unity Version Control Settings

Steps to reproduce:

1. Create a new Unity project using the Universal 3D template
2. Click the "Unity VCS" dropdown in the Customizable Toolbar
3. Click the "Use Unity Version Control..." button
4. Click the "Create Workspace" in the Unity Version Control window
5. Click the "Create Workspace" button again
6. Open the Unity Version Control Settings by clicking the cogwheel button in the Unity Version Control window
7. Observe the Default, Result encoding properties under the Diff and Merge Options

Actual results: The property dropdowns are blank/empty by default until the user selects something in the dropdown

Expected results: The dropdowns are not empty

Reproducible with versions: 6000.0.0f1, 6000.0.75f1, 6000.3.16f1, 6000.4.8f1, 6000.5.0b9, 6000.6.0a5

Tested on (OS): MacOS Silicon Tahoe 26.3, Ubuntu 24.04