Use `FastDateFormat` as the legacy fractional formatter

By default HiveResult.hiveResultString retrieves timestamps values as instances of java.sql.Timestamp, and uses the legacy parser SimpleDateFormat to convert the timestamps to strings. After the fix #28024, the fractional formatter and its companion - legacy formatter SimpleDateFormat are created per every value. By switching from LegacySimpleTimestampFormatter to LegacyFastTimestampFormatter, we can utilize the internal cache of FastDateFormat, and avoid parsing the default pattern yyyy-MM-dd HH:mm:ss.