test: improve crypto/random.js coverage

- Call randomBytes with a non-function callback
- Call randomFill with a non-function callback

PR-URL: https://github.com/nodejs/node/pull/17555


Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>