test: handle EPIPE in closed channel test

The second handle is only sent once the first one is acknowledged, by
which time the worker may already have exited, so the write can fail
with EPIPE. Observed on AIX in the CI reliability report of 2026-09-04.

Signed-off-by: Christian Aurich <christian.aurichzm@gmail.com>
PR-URL: #65770
Refs: nodejs/reliability#1650
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

Author: christianaurichzm

test/parallel/test-child-process-fork-closed-channel-segfault.js

@@ -76,6 +76,7 @@ const server = net
           // Ignore errors when sending the second handle because the worker
           // may already have exited.
           if (err && err.code !== 'ERR_IPC_CHANNEL_CLOSED' &&
+                     err.code !== 'EPIPE' &&
                      err.code !== 'ECONNRESET' &&
                      err.code !== 'ECONNREFUSED' &&
                      err.code !== 'EMFILE') {