Modded victory types are not removed from `gameParameters` after mod is unloaded

[OptimizedForDensity]

I stumbled upon this in the latest repo version. To test,

1. Load a mod that adds a custom victory condition (e.g., Alpha Frontier)
2. Select custom victory type (for Alpha Frontier, select "Terraforming")
3. Unload mod
4. Launch a game with a breakpoint in GameStarter.startNewGame(gameSetupInfo) and inspect gameSetupInfo.gameParameters