Chore: Remove ctlcmd and leftover envvar (#5392)

https://github.com/v2fly/v2ray-core/issues/360

common/platform/windows.go

@@ -5,20 +5,10 @@ package platform
 
 import "path/filepath"
 
-func ExpandEnv(s string) string {
-	// TODO
-	return s
-}
-
 func LineSeparator() string {
 	return "\r\n"
 }
 
-func GetToolLocation(file string) string {
-	toolPath := NewEnvFlag(ToolLocation).GetValue(getExecutableDir)
-	return filepath.Join(toolPath, file+".exe")
-}
-
 // GetAssetLocation searches for `file` in the env dir and the executable dir
 func GetAssetLocation(file string) string {
 	assetPath := NewEnvFlag(AssetLocation).GetValue(getExecutableDir)