go2rtc is not running in this test, so the gateway cannot reach it and
the message "its go2rtc answered (as a refusal)" was wrong. What the
assertion really establishes is that the offer travelled
cloud -> uplink -> gateway at all, which a timeout would not.
Records that the happy path was verified by hand - the real go2rtc and a
valid offer return 200 with an answer SDP carrying go2rtc's own host and
server-reflexive candidates - and why that is not automated here: it
needs a live camera and go2rtc installed, and this script should not
depend on either.