"Runtime" and "Editor (for Editor Extension Authoring) fields are rendered inconsistently compared to other settings fields in the same window

Steps to reproduce:

1. Create a new Unity project
2. Create a new Unity Default Runtime Theme (Create > UI Toolkit > Unity Default Runtime Theme File)
3. Rename the newly created file to a longer title
4. Open "Project Settings" (Edit > Project Settings)
5. Select the "UI Toolkit" and find the "Project Preview Theme" section
6. Verify that the newly created theme title is displayed in the "Runtime" and "Editor (for Editor Extension Authoring) fields 
7. Resize the window and observe how these two fields are rendered compared with all other fields in the same window
8. Dock the "Project Settings" window next to the "Game" field
9. Observe how these two fields are displayed in a docked view

Actual results: In Project Settings → UI Toolkit, the Runtime and Editor Theme fields are rendered inconsistently compared to other settings fields in the same window. These fields use a different layout behavior, extending into the right side of the panel and creating excessive space, misalignment, or an oversized field area.

Expected results: In Project Settings → UI Toolkit, the Runtime and Editor Theme fields should be rendered using the same layout rules as all other settings fields in the window. Long theme titles should be truncated with "...".

Reproducible with versions: 6000.4.0b3, 6000.5.0a4

Tested on (OS): macOS - Tahoe 26.2