Entity Baking Preview dropdown is empty and interactable when selecting a prefab while no SubScene has been created

Steps to reproduce:

1. Create a new URP project
2. Install Entities (com.unity.entities) package
3. In the Hierarchy, right-click > Create Empty GameObject 
4. Drag it to the Project window to create a Prefab
5. Select in in the Project window
6. In the Inspector, observe the dropdown next to "Entity Baking Preview"

Actual results: The dropdown is completely empty, and clicking on it has no functionality

Expected results: The dropdown should be disabled (greyed out) or hidden entirely when the condition is not met

Reproducible with versions: 2023.3.0b1, 6000.0.71f1, 6000.3.12f1, 6000.4.1f1, 6000.5.0b3, 6000.6.0a2

Can’t test with versions: 2023.1.0a3 (due to no Entities package)

Tested on (OS): macOS 26.3

Notes:

• Once a SubScene is created, the dropdown populates with options
• If the SubScene is removed, the dropdown still shows the "Editor World" option. This might indicate that "Editor World" should just be the default populated state from the start instead of being empty