test: fix flaky test-http-set-timeout-server

It can happen that the connection and server is closed before the second
reponse has been processed by server. In this case, the
`res.setTimeout()` callback will never be called causing the test to
fail. Fix this by only closing the connection and server when the 2nd
has been received.
PR-URL: #11790Fixes: #11768
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>

Author: santigimeno

test/parallel/test-http-set-timeout-server.js

@@ -117,20 +117,25 @@ test(function serverRequestNotTimeoutAfterEnd(cb) {
 
 test(functionserverResponseTimeoutWithPipeline(cb){
 letcaughtTimeout='';
+letsecReceived=false;
 process.on('exit',function(){
 assert.strictEqual(caughtTimeout,'/2');
 });
 constserver=http.createServer(function(req,res){
+if(req.url==='/2')
+secReceived=true;
 consts=res.setTimeout(50,function(){
 caughtTimeout+=req.url;
 });
 assert.ok(sinstanceofhttp.OutgoingMessage);
 if(req.url==='/1')res.end();
 });
 server.on('timeout',function(socket){
-socket.destroy();
-server.close();
-cb();
+if(secReceived){
+socket.destroy();
+server.close();
+cb();
+}
 });
 server.listen(common.mustCall(function(){
 constport=server.address().port;