OpenXR: “+” in the "Enabled Interaction Profiles" appears active despite no available profiles to add

Steps to reproduce:

1. Create a Unity project
2. Go to "Edit -> Project Settings"
3. Select the "XR Plugin Management"
4. Click the "Install XR Plugin Management" button in the details window
5. Check the "Open XR" in the "XR Plug-in Management" window
6. Select the "OpenXR" newly listed setting, which should be visible under the "XR Plugin Management"
7. Add all possible interaction profiles in the "Enabled Interaction Profiles" section
8. Click "+" one more time, even though there is nothing to add
9. Observe the result

Actual results: "+" is still displayed as active

Expected results:  "+" should be displayed as inactive as "-" is inactive at the begining

Reproducible with versions: 1.17.0-pre.1(6000.4.0b8, 6000.5.0a7)

Tested on (OS): macOS - Tahoe 26.3