refine export cleaner (#2916)

* refine export cleaner

cmd/backup-manager/app/clean/clean.go

@@ -68,6 +68,12 @@ func (bo *Options) cleanRemoteBackupData(bucket string, opts []string) error {
 	args := util.ConstructArgs(constants.RcloneConfigArg, opts, "deletefile", destBucket, "")
 	output, err := exec.Command("rclone", args...).CombinedOutput()
 	if err != nil {
+		if exitError, ok := err.(*exec.ExitError); ok {
+			if code := exitError.ExitCode(); code == 3 || code == 4 {
+				klog.Infof("cluster %s backup %s has already been deleted before", bo, bucket)
+				return nil
+			}
+		}
 		return fmt.Errorf("cluster %s, execute rclone deletefile command failed, output: %s, err: %v", bo, string(output), err)
 	}