test: deflake esm loader http imports

Keep idle server connections open until the client closes them. This
avoids reusing a keep-alive socket the server closed while the loader
thread was stalled.

Refs: #47836
Signed-off-by: Filip Skokan <panva.ip@gmail.com>
Assisted-by: Claude, Codex
PR-URL: #66320
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>

Author: panva

test/es-module/es-module.status

@@ -6,10 +6,6 @@ prefix es-module
 
 [true] # This section applies to all platforms
 
-[$system==linux || $system==freebsd]
-# https://github.com/nodejs/node/issues/47836
-test-esm-loader-http-imports: PASS,FLAKY
-
 [$arch==arm || $arch==arm64]
 # https://github.com/nodejs/node/issues/47297
 test-wasm-web-api: SKIP

test/es-module/test-esm-loader-http-imports.mjs

@@ -34,7 +34,9 @@ const requestListener = ({ url }, rsp) => {
     .end();
 };
 
-const server = http.createServer(requestListener);
+// Leave closing idle connections to the client, so that the loader never
+// reuses a keep-alive socket the server has just closed.
+const server = http.createServer({ keepAliveTimeout: 0 }, requestListener);
 
 await promisify(server.listen.bind(server))({
   host: '127.0.0.1',