test: pin auth_hmac fixed wire vectors and widen negative coverage

A sign and verify round trip cannot expose a wire deviation, so the
test now checks the fixed appendix images carrying the RFC 9568
message only IPv4 checksum, one flipped byte per field, and the
window, clock step and replay mark behavior.

Signed-off-by: Alexandre Cassen <acassen@gmail.com>
Suggested-by: Aditya Dogra <addogra@cisco.com>