pruning some codes

Co-Authored-By: Alireza Ahmadi <alireza7@gmail.com>

util/common/err.go

@@ -6,8 +6,6 @@ import (
 	"x-ui/logger"
 )
 
-var CtxDone = errors.New("context done")
-
 func NewErrorf(format string, a ...interface{}) error {
 	msg := fmt.Sprintf(format, a...)
 	return errors.New(msg)

util/common/stringUtil.go

@@ -1,9 +0,0 @@
-package common
-
-import "sort"
-
-func IsSubString(target string, str_array []string) bool {
-	sort.Strings(str_array)
-	index := sort.SearchStrings(str_array, target)
-	return index < len(str_array) && str_array[index] == target
-}