refactor: replace HasPrefix+TrimPrefix with CutPrefix

Signed-off-by: jinjiadu <jinjiadu@aliyun.com>

pkg/ignore/rules.go

@@ -170,10 +170,10 @@ func (r *Rules) parseRule(rule string) error {
 		rule = strings.TrimSuffix(rule, "/")
 	}
 
-	if strings.HasPrefix(rule, "/") {
+	if after, ok := strings.CutPrefix(rule, "/"); ok {
 		// Require path matches the root path.
 		p.match = func(n string, _ os.FileInfo) bool {
-			rule = strings.TrimPrefix(rule, "/")
+			rule = after
 			ok, err := filepath.Match(rule, n)
 			if err != nil {
 				slog.Error("failed to compile", "rule", rule, slog.Any("error", err))