UUM - Play Mode Scenarios add and remove element list buttons go out of their bounds when the window is resized

Steps to reproduce:

1. Create a new Unity project using the Universal 3D template
2. Install the Multiplayer Play Mode package
3. Open the Play Mode Scenarios window (Window > Multiplayer > Play Mode Scenarios)
4. Create a new Play Mode Scenario
5. Expand the "Additional Editor Instances" and "Local Instances" dropdowns
6. Resize the middle divider in the window to make the right section smaller
7. Observe the Play Mode Scenarios window

Actual results: Add and remove element list buttons go out of their bounds

Expected results: List element buttons remain attached to the list

Reproducible with versions: 6000.0.61f1, 6000.2.10f1, 6000.3.0b8, 6000.4.0a3, 6000.5.0a2

Tested on (OS): MacOS Silicon Sequoia 15.6.1, Windows 11