[Feature][JDBC] Improve the jdbc parallel-reader generated sql

[liunaijie]

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Description

In JDBC connector.
JDBC connector has a parallel-reader feature.
It can split the user big query to multiple small query.

The generated sql pattern is like this:

select * from (user special sql) where md5(partition_col) % total_paraliam = current_paraliam_index

But there has a problem if the user special sql contains sql hints.
For example, the user query is

SELECT /*+ SET_VAR(query_timeout = 6000) */ col_a, col_b from table_a

After sql re-generate, the executed sql would be

select * from ( SELECT /*+ SET_VAR(query_timeout = 6000) */ col_a, col_b  from table_a )  xxxxx

Then the sql hint will be ignore.

Usage Scenario

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Related issues

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Are you willing to submit a PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct

[liunaijie]

Related code:

• https://github.com/apache/seatunnel/blob/dev/seatunnel-connectors-v2/connector-jdbc/src/main/java/org/apache/seatunnel/connectors/seatunnel/jdbc/source/FixedChunkSplitter.java#L119
• https://github.com/apache/seatunnel/blob/dev/seatunnel-connectors-v2/connector-jdbc/src/main/java/org/apache/seatunnel/connectors/seatunnel/jdbc/source/FixedChunkSplitter.java#L191