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.
fix http-rules/h00000.vtc / http-rules/h00000.vtc as both 'bodylen' and
'body' are specified, these settings conflict with each other as they
both generate/present the body to send.
The HTTP rules test now runs an H1 and an H2 client. Since the H2 one
requires the "proto" directive on the bind line, a new file has been
created requiring version 1.9 and the previous one was marked as usable
below 1.9 so that it's skipped by default but still usable when testing
backports.