QUIC: set NGX_TCP_NODELAY_DISABLED for fake stream connections.

Notably, it is to avoid setting the TCP_NODELAY flag for QUIC streams
in ngx_http_upstream_send_response().  It is an invalid operation on
inherently SOCK_DGRAM sockets, which leads to QUIC connection close.

The change reduces diff to the default branch in stream content phase.

src/event/quic/ngx_event_quic_streams.c

@@ -450,6 +450,7 @@ ngx_quic_create_stream(ngx_connection_t *c, uint64_t id)
     sc->local_sockaddr = c->local_sockaddr;
     sc->local_socklen = c->local_socklen;
     sc->number = ngx_atomic_fetch_add(ngx_connection_counter, 1);
+    sc->tcp_nodelay = NGX_TCP_NODELAY_DISABLED;
 
     sc->recv = ngx_quic_stream_recv;
     sc->send = ngx_quic_stream_send;

src/stream/ngx_stream_core_module.c

@@ -325,9 +325,6 @@ ngx_stream_core_content_phase(ngx_stream_session_t *s,
     cscf = ngx_stream_get_module_srv_conf(s, ngx_stream_core_module);
 
     if (c->type == SOCK_STREAM
-#if (NGX_STREAM_QUIC)
-        && c->quic == NULL
-#endif
         && cscf->tcp_nodelay
         && ngx_tcp_nodelay(c) != NGX_OK)
     {