[BUG] SQL Join timeout isn't applied when using PIT

What is the bug?
When using a JOIN timeout hint with a PIT-enabled cluster, the PIT will get deleted before the timeout expires.

Caused by: java.lang.IllegalArgumentException: Point In Time id: [y_T7MwDnSG-rblpw9Xa6mQ] doesn't exist

This is due to a 1-minute keepalive https://github.com/opensearch-project/sql/blob/35518dc185253e78f48b48184c37954ace576e63/opensearch/src/main/java/org/opensearch/sql/opensearch/setting/OpenSearchSettings.java#L61

Used by PIT at https://github.com/opensearch-project/sql/blob/35518dc185253e78f48b48184c37954ace576e63/legacy/src/main/java/org/opensearch/sql/legacy/pit/PointInTimeHandlerImpl.java#L59

How can one reproduce the bug?
Steps to reproduce the behavior:

1. Create indices that require more than 60s to join on (>5 mil records each)
2. Configure the cluster to use PIT joins per https://github.com/opensearch-project/sql/blob/35518dc185253e78f48b48184c37954ace576e63/docs/dev/opensearch-pagination.md?plain=1#L497
3. Run a join query with a longer join timeout hint /*! JOIN_TIME_OUT(90) */
4. See in the logs that the join failed because the PIT no longer exists (deleted by the 1m keepalive)

What is the expected behavior?
The JOIN_TIME_OUT should also update the keepalive

What is your host/environment?

• OS: Latest

Do you have any screenshots?
N/A

Do you have any additional context?
Add any other context about the problem.

Start with opensearch/src/main/java/org/opensearch/sql/opensearch/setting/OpenSearchSettings.java and legacy/src/main/java/org/opensearch/sql/legacy/pit/PointInTimeHandlerImpl.java, then review the PIT configuration described in docs/dev/opensearch-pagination.md. Ensure a JOIN_TIME_OUT longer than the default keepalive keeps the PIT available through the join, and verify the reported timeout scenario no longer fails because the PIT was deleted.