n-api: remove n-api module loading flag

Remove the command line flag that was needed for N-API module loading.
Re: https://github.com/nodejs/vm/issues/9

Backport-PR-URL: https://github.com/nodejs/node/pull/19447
PR-URL: https://github.com/nodejs/node/pull/14902


Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Hitesh Kanwathirtha <digitalinfinity@gmail.com>