Remove unused environment variables

Author: DashingCat

Celeste.Mod.mm/Mod/Everest/Everest.cs

@@ -291,12 +291,6 @@ internal static void ParseArgs(string[] args) {
                 else if (arg == "--dump-all")
                     Content._DumpAll = true;
 
-                else if (arg == "--headless")
-                    Environment.SetEnvironmentVariable("EVEREST_HEADLESS", "1");
-
-                else if (arg == "--everest-disabled")
-                    Environment.SetEnvironmentVariable("EVEREST_DISABLED", "1");
-
                 else if (arg == "--whitelist" && queue.Count >= 1)
                     Loader.NameWhitelist = queue.Dequeue();