REGTESTS: adjust the http-rules regtest to support window updates

Varnishtest is not happy to see the window update come before the
settings ACK, as by default it expects exactly tx/rx/txack/rxack.
One workaround could consist in making haproxy send the WU after
the settings ACK but this would be a real hack as the preface is
already finished when sending this ack. Instead, let's make the
initial sequence explicit in the tests.
2 files changed