[Bug] The starrocks connector unknown datatype handle method maybe need to change

[XiaoYou201]

The starrocks connector handle UNKNOWN data type as same as json. It is unreasonable. So, it need to be modified.

starrocks-connector-for-apache-flink/src/main/java/com/starrocks/connector/flink/row/sink/StarRocksTableRowTransformer.java

Lines 126 to 135 in cc8689d

	case VARCHAR:
	String sValue = record.getString(pos).toString();
	if (columns == null) {
	return sValue;
	}
	StarRocksDataType starRocksDataType =
	columns.getOrDefault(columnNames[pos], StarRocksDataType.UNKNOWN);
	if ((starRocksDataType == StarRocksDataType.JSON ||
	starRocksDataType == StarRocksDataType.UNKNOWN)
	&& (sValue.charAt(0) == '{' || sValue.charAt(0) == '[')) {

In my opinion, if data type is unknown, we should return origin data.

For example, while starrocks table not has a column named c1, but the user insert data has c1 and c1 value is ""(blank string) through flink, it will encounter IndexOfRangeException.