Revert "readline: clean up event listener in onNewListener"

This reverts commit 81ddeb98.

Ref: https://github.com/nodejs/node/pull/13266
PR-URL: https://github.com/nodejs/node/pull/13560


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>