rgw/kms/vault - rework unit test logic for new transit logic.

rgw/kms/vault - rework unit test logic for new transit logic.

The "new" transit logic is organized quite differently
than the old logic, so the existing unit test logic was
very broken.  Additionally, it's possible to test the
input arguments and send_request() has more of them now,
so add logic to verify most of those arguments are correct.

Fixes: http://tracker.ceph.com/issues/48746
Signed-off-by: Marcus Watts <mwatts@redhat.com>