issue #3153: return XAER_NOTA on rollback

[jmfinelli]

Changes to Existing Features:

• Does this break existing behaviour? If so please explain.
  • It does not break existing behaviour
• Have you added an explanation of what your changes do and why you'd like us to include them?
  • Yep, I wrote an explanation in the related issue (org.postgresql.xa.PGXAConnection.rollback(Xid) should return XAER_NOTA #3153)
• Have you written new tests for your core changes, as applicable?
  • I modified a test of XADataSourceTest
• Have you successfully run tests with your changes locally?
  • Yes, I have tested my changes using ./gradlew test