Quality Levels accept special characters which cause undesireable effects

Steps to reproduce:

1. Create and open a new 3D URP project
2. Open Edit -> Project Settings -> Quality
3. Rename the bottom Quality level to "&/&/&"
4. Open the 'default level' dropdown
5. Observe the options in the dropdown

Actual results: One of the options is a path with empty strings

Expected results: The name is invalid, and a default value of 'Level <index>' is assigned and displayed in the dropdown 

Reproducible with versions: 6000.0.0f1, 6000.0.76f1, 6000.3.17f1, 6000.4.10f1, 6000.5.0b11, 6000.6.0a6

Tested on (OS): Windows 11 Pro (25H2)

Notes:

• / - makes a path from the string
• & - creates an empty character (unless '&&' is typed, then only one & will be displayed)
• Most special characters do not affect the quality level names
• Special characters should generally be invalid in names