http: set socket.server unconditionally

This is useful for situations in which the socket was not
created for HTTP, e.g. when using arbitrary `Duplex` streams.

(The added test fails because previously, `socket.server.emit()`
would not work for emitting the `clientError` event, as
`socket.server` was `undefined`.)

PR-URL: #30571
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

lib/_http_server.js

@@ -369,8 +369,7 @@ function connectionListenerInternal(server, socket) {
 
   // Ensure that the server property of the socket is correctly set.
   // See https://github.com/nodejs/node/issues/13435
-  if (socket.server === null)
-    socket.server = server;
+  socket.server = server;
 
   // If the user has added a listener to the server,
   // request, or response, then it's their responsibility.

test/parallel/test-http-generic-streams.js

@@ -138,3 +138,17 @@ const MakeDuplexPair = require('../common/duplexpair');
   req.write(testData);
   req.end();
 }
+
+// Test 5: The client sends garbage.
+{
+  const server = http.createServer(common.mustNotCall());
+
+  const { clientSide, serverSide } = MakeDuplexPair();
+  server.emit('connection', serverSide);
+
+  server.on('clientError', common.mustCall());
+
+  // Send something that is not an HTTP request.
+  clientSide.end(
+    'I’m reading a book about anti-gravity. It’s impossible to put down!');
+}