Release TransactionDB path string after multi-CF open

[verma-divyanshu-git]

Summary

Release the database path returned by GetStringUTFChars after the multi-column-family TransactionDB::Open call.

This matches the resource handling in the single-column-family and OptimisticTransactionDB implementations.

Fixes #14893

Test plan

• Built the RocksJava JNI library and Java tests.
• Ran TransactionDBTest with -Xcheck:jni: 11 tests passed.
• Ran the complete RocksJava test suite: 1,248 tests passed.
• Repeated the focused test under macOS leaks and confirmed the original GetStringUTFChars leak stack is no longer present.
• Ran make check-format and git diff --check.

[verma-divyanshu-git]

@adamretter Would you be able to review this small RocksJava JNI resource-lifetime fix, or point me to the appropriate reviewer?

It follows the existing release pattern in the single-column-family and OptimisticTransactionDB implementations. The CLA and Meta Import Checks are green, while the internal Import Status is still queued. The focused leak verification and full RocksJava test results are included in the PR description.

@K-ANOY, this addresses the leak reported in #14893; any verification would be appreciated.

[K-ANOY]

Looks good to me. This fixes the reported leak.