Separation Line is used at the bottom of Prefab dropdown options when there is nothing to separate

Steps to reproduce:

1. Create any Project
2. Import the attached Unity Package
3. Open Scene "Arena_v1_MP_Prototype"
4. In the Hierarchy search for "BigSupportElement2Bs"
5. Right click it and choose "Prefab"
6. Observe the "Prefab" options menu

Actual results: A separation line at the bottom is used

Expected results: No separation line is used when there is no option to separate from

Reproducible with versions: 2022.3.64f1, 6000.0.54f1, 6000.1.12f1, 6000.2.0b10

Tested on (OS): Windows 11