[BugFix] Fix JDBC kill task not cleaning up DDL state (#5320)

[zhang-arvin]

What is the purpose of the change

Fix JDBC engine kill task not cleaning up DDL state. When a DDL statement (CREATE TABLE/VIEW) is being executed and the task is killed mid-execution, the partially created objects should be cleaned up by issuing DROP IF EXISTS statements.

Brief change log

• Store the executing SQL code in executeLine using taskCodeMap
• When killTask is called, parse the original SQL for DDL statements (CREATE TABLE/VIEW)
• Generate corresponding DROP IF EXISTS statements to clean up partially created objects
• Execute cleanup DDL using the existing connection before killing the task

Verifying this change

This change ensures that when a user kills a DDL task, any partially created tables or views are properly cleaned up.

Does this pull request potentially affect one of the following parts:

• Dependencies (no)
• Anything that affects deployment (no)
• The Core framework (no)