test: improve crypto test coverage

- Call Sign without new
- Call Verify without new
- Call Verify#verify with options.padding !== options.padding >> 0
- Call Verify#verify with options.saltLength !== options.saltLength >> 0

PR-URL: https://github.com/nodejs/node/pull/17426


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