Introduce EJB-based transactional tests in the TCF

This commit introduces JUnit-based transactional tests in the
TestContext framework using @TransactionAttribute in EJBs instead of
Spring’s @Transactional annotation.

Issue: SPR-6132
Introduce EJB-based transactional tests in the TCF

This commit introduces TestNG-based transactional tests in the
TestContext framework using @TransactionAttribute in EJBs instead of
Spring’s @Transactional annotation.

Issue: SPR-6132