Tests: removed a duplicate HTTP/2 graceful shutdown test.

A similar (and better) test exists for GOAWAY with active streams.
diff --git a/h2.t b/h2.t
index 7f54288..2659424 100644
--- a/h2.t
+++ b/h2.t
@@ -111,7 +111,6 @@
         server_name  localhost;
 
         client_header_timeout 1s;
-        send_timeout 1s;
     }
 
     server {
@@ -1116,12 +1115,6 @@
 my $grace = Test::Nginx::HTTP2->new(port(8084));
 $grace->new_stream({ split => [ 9 ], abort => 1 });
 
-# graceful shutdown with stream waiting on WINDOW_UPDATE
-
-my $grace2 = Test::Nginx::HTTP2->new(port(8084));
-$sid = $grace2->new_stream({ path => '/t1.html' });
-$grace2->read(all => [{ sid => $sid, length => 2**16 - 1 }]);
-
 # graceful shutdown waiting on incomplete request body DATA frames
 
 my $grace3 = Test::Nginx::HTTP2->new(port(8085));