Fix JDBC connection lifecycle in GenericJdbcExecutor

[harshitsingh070]

Summary

Restore the intended JDBC connection lifecycle in GenericJdbcExecutor.

Root Cause

GenericJdbcExecutor declared a JDBC Connection, but connection initialization was commented out. The commented code also used an outdated createDatabaseDescriptor signature.

As a result, the executor's connection remained null, while the corresponding connection cleanup in dispose() was also commented out.

Changes

• Initialize the JDBC connection using the current createDatabaseDescriptor API.
• Use the genericjdbc configuration namespace when creating the database descriptor.
• Close the JDBC connection in dispose().
• Add regression tests covering connection creation and disposal.

Testing

Ran:

.\mvnw.cmd test -pl wayang-platforms/wayang-generic-jdbc -Pskip-prerequisite-check

Result:

Tests run: 4
Failures: 0
Errors: 0
Skipped: 0
BUILD SUCCESS