(7.4.z) Adapt JaccInitializationTestCase to work on SE 17

JaccInitializationTestCase contains one method that tests legacy security, which should be disabled on SE 17, and then a number of other methods that setup elytron and later restore legacy security, which shouldn't be done on SE 17. The 'SE17-ized' config the test starts with already has elytron set up and a 'restoration' shouldn't move away from elytron.