Edge case of displaying no chosen challenge as "cmd_change_challenge" when the saved one goes missing

[WhenTanksFly]

1. Have the lobby creation interface remember a non-vanilla challenge being picked
2. Get rid of said challenge (I threw the .vpk out of the addons folder and restarted the game)
3. Back to lobby settings, see "Challenge: Disabled" like normal
4. Open the list of available challenges, notice the topmost line "Disabled" not being highlighted
5. Nope out without selecting any challenge
6. You now see "Challenge: cmd_change_challenge" instead of "Challenge: Disabled"