Tests: fixed HTTP/2 test with invalid PROXY protocol string.

Previously it tested invalid connection preface.

h2_proxy_protocol.t

diff --git a/h2_proxy_protocol.t b/h2_proxy_protocol.t
index eb8a89d..d1b539c 100644
--- a/h2_proxy_protocol.t
+++ b/h2_proxy_protocol.t
@@ -39,7 +39,6 @@
     %%TEST_GLOBALS_HTTP%%
 
     server {
-        listen       127.0.0.1:8080 http2;
         listen       127.0.0.1:8081 proxy_protocol http2;
         server_name  localhost;
 
@@ -70,8 +69,9 @@
 
 # invalid PROXY protocol string
 
-my $s = http('BOGUS TCP4 192.0.2.1 192.0.2.2 1234 5678', start => 1);
-$frames = h2_read({ socket => $s }, all => [{ type => 'GOAWAY' }]);
+$proxy = 'BOGUS TCP4 192.0.2.1 192.0.2.2 1234 5678' . CRLF;
+$sess = new_session(8081, preface => $proxy, pure => 1);
+$frames = h2_read($sess, all => [{ type => 'GOAWAY' }]);
 
 ($frame) = grep { $_->{type} eq "GOAWAY" } @$frames;
 ok($frame, 'invalid PROXY - GOAWAY frame');