mysql(ticdc): remove error filter when check isTiDB in backend init (p…

…ingcap#11214) (pingcap#11261)

close pingcap#11213

pkg/sink/mysql/db_helper.go

@@ -318,12 +318,7 @@ func CheckIsTiDB(ctx context.Context, db *sql.DB) (bool, error) {
 	err := row.Scan(&tidbVer)
 	if err != nil {
 		log.Error("check tidb version error", zap.Error(err))
-		// downstream is not TiDB, do nothing
-		if mysqlErr, ok := errors.Cause(err).(*dmysql.MySQLError); ok && (mysqlErr.Number == tmysql.ErrNoDB ||
-			mysqlErr.Number == tmysql.ErrSpDoesNotExist || mysqlErr.Number == tmysql.ErrDBaccessDenied) {
-			return false, nil
-		}
-		return false, errors.Trace(err)
+		return false, nil
 	}
 	return true, nil
 }