test: improve coverage on removeListeners functions

PR-URL: https://github.com/nodejs/node/pull/11140


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Italo A. Casas <me@italoacasas.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>