stream: do not deadlock duplexpair

If nothing is buffered then _read will not be called and the
callback will not be invoked, effectivly deadlocking.

Fixes: https://github.com/nodejs/node/issues/29758

PR-URL: https://github.com/nodejs/node/pull/29836
Refs: https://github.com/nodejs/node/pull/29649


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>