test: dynamic port in cluster worker wait close

Remove common.PORT from test-cluster-worker-wait-server-close
possibility that a dynamic port used in another test will collide
with common.PORT.

PR-URL: https://github.com/nodejs/node/pull/12466
Ref: https://github.com/nodejs/node/issues/12376
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>

test/parallel/test-cluster-worker-wait-server-close.js

@@ -12,7 +12,7 @@ if (cluster.isWorker) {
     // Wait for any data, then close connection
     socket.write('.');
     socket.on('data', function discard() {});
-  }).listen(common.PORT, common.localhostIPv4);
+  }).listen(0, common.localhostIPv4);
 
   server.once('close', function() {
     serverClosed = true;
@@ -33,8 +33,8 @@ if (cluster.isWorker) {
   const worker = cluster.fork();
 
   // Disconnect worker when it is ready
-  worker.once('listening', function() {
-    const socket = net.createConnection(common.PORT, common.localhostIPv4);
+  worker.once('listening', function(address) {
+    const socket = net.createConnection(address.port, common.localhostIPv4);
 
     socket.on('connect', function() {
       socket.on('data', function() {