[BUG] JDBC doesn't return second fraction part for timestamp

What is the bug?

Reason: manual parsing of timestamp values
https://github.com/opensearch-project/sql/blob/c923e80cd654ee8136c74180bf0bd6231044ff71/sql-jdbc/src/main/java/org/opensearch/jdbc/types/TimestampType.java#L63-L96

How can one reproduce the bug?

select timestamp("1970-01-01 12:00:00.501");

JDBC output:

SQL plugin output:

fetched rows / total rows = 73/73
+-------------------------+--------------------------------+
| val                     | key                            |
|-------------------------+--------------------------------|
| null                    | null                           |
| 1899-01-01 20:00:00     | 001: 1899-01-01 12:00:00       |
| 1899-12-31 20:00:00     | 002: 1899-12-31 12:00:00       |
| 1940-02-29 20:00:00     | 003: 1940-02-29 12:00:00       |
| 1970-01-01 08:00:00     | 004: 1970-01-01 00:00:00-epoch |
| 1970-01-01 08:00:01     | 005: 1970-01-01 00:00:01       |
| 1970-01-01 09:00:00     | 006: 1970-01-01 01:00:00       |
| 1970-01-01 09:59:00     | 007: 1970-01-01 01:59:00       |
| 1970-01-01 09:59:59     | 008: 1970-01-01 01:59:59       |
| 1970-01-01 10:00:00     | 009: 1970-01-01 02:00:00       |
| 1970-01-01 10:00:01     | 010: 1970-01-01 02:00:01       |
| 1970-01-01 10:30:00.1   | 011: 1970-01-01 02:30:00.1     |
| 1970-01-01 11:00:00.2   | 012: 1970-01-01 03:00:00.2     |
| 1970-01-01 12:00:00.3   | 013: 1970-01-01 04:00:00.3     |
| 1970-01-01 13:00:00.4   | 014: 1970-01-01 05:00:00.4     |
| 1970-01-01 14:00:00.5   | 015: 1970-01-01 06:00:00.5     |
| 1970-01-01 15:00:00.6   | 016: 1970-01-01 07:00:00.6     |
| 1970-01-01 16:00:00.7   | 017: 1970-01-01 08:00:00.7     |
| 1970-01-01 17:00:00.8   | 018: 1970-01-01 09:00:00.8     |
| 1970-01-01 18:00:00.9   | 019: 1970-01-01 10:00:00.9     |
| 1970-01-01 19:59:00.499 | 020: 1970-01-01 11:59:00.499   |
| 1970-01-01 19:59:59.5   | 021: 1970-01-01 11:59:59.500   |
| 1970-01-01 20:00:00.501 | 022: 1970-01-01 12:00:00.501   |

What is the expected behavior?

Use API for parsing, e.g. Timestamp.valueOf method:

java.sql.Timestamp.valueOf("1970-01-01 12:00:00.501") = 1970-01-01 12:00:00.501

What is your host/environment?

2.x @ e2bf2544

Start with sql-jdbc/src/main/java/org/opensearch/jdbc/types/TimestampType.java, especially lines 63-96, and reproduce the issue with select timestamp("1970-01-01 12:00:00.501"). Compare the JDBC result with java.sql.Timestamp.valueOf and verify that the returned timestamp preserves the fractional seconds shown by the SQL plugin output.