Fix ArrayIndexOutOfBoundsException in CascadeDeletesJUnitTestSuite

The test CascadeDeletesJUnitTestSuite.testDeletePrivateOwned fails
occasionally with an ArrayIndexOutOfBoundsException. This happens when
the test picks a different related entity from a OneToMany relationship
that the test actually intends to.
Adding an @OrderBy annotation to the relationship guarantees that always
the desired entity is retrieved.

Bug 401413

Signed-off-by: Sabine Heider <sabine.heider@sap.com>