0-rtt regtest

[chipitsine]

The commit of ea8dd94 seems to break
the allow-0rtt in server line, a connection will take very very long
to complete. Remove allow-0rtt it turns normal.

conf like:

listen test
mode tcp
bind 0.0.0.0:88
default_backend tls
backend tls
mode tcp
retry-on 0rtt-rejected conn-failure empty-response response-timeout
server default x.x.x.x:4433 allow-0rtt ssl check inter 300s alpn h2
verify none