net: make writeAfterFIN() return false

If `false` is not returned a readable stream piped into the socket
might continue reading indefinitely until the process goes out of
memory.

PR-URL: https://github.com/nodejs/node/pull/27996


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>