test: deflake test-http-many-ended-pipelines

The socket might be destroyed by the other peer while data is still
being written. Add the missing error handler.

Fixes: #37291

test/parallel/test-http-many-ended-pipelines.js

@@ -29,6 +29,7 @@ console.trace = function() {
   throw new Error('no tracing should happen here');
 };
 
+const assert = require('assert');
 const http = require('http');
 const net = require('net');
 
@@ -51,6 +52,13 @@ const server = http.createServer(function(req, res) {
 server.listen(0, function() {
   const client = net.connect({ port: this.address().port,
                                allowHalfOpen: true });
+
+  client.on('error', function(err) {
+    // The socket might be destroyed by the other peer while data is still
+    // being written.
+    assert.strictEqual(err.code, 'ECONNRESET');
+  });
+
   for (let i = 0; i < numRequests; i++) {
     client.write('GET / HTTP/1.1\r\n' +
                  'Host: some.host.name\r\n' +