Change default preset to secret (#8694)

It gets voted for at the start every time anyway and traitor isn't even voteable.

Content.Shared/CCVar/CCVars.cs

@@ -124,7 +124,7 @@ namespace Content.Shared.CCVar
         ///     Controls the default game preset.
         /// </summary>
         public static readonly CVarDef<string>
-            GameLobbyDefaultPreset = CVarDef.Create("game.defaultpreset", "traitor", CVar.ARCHIVE);
+            GameLobbyDefaultPreset = CVarDef.Create("game.defaultpreset", "secret", CVar.ARCHIVE);
 
         /// <summary>
         ///     Controls if the game can force a different preset if the current preset's criteria are not met.