tools: speed up lint-md-build

by using package-lock.json

PR-URL: https://github.com/nodejs/node/pull/16945
Fixes: https://github.com/nodejs/node/issues/16628


Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Khaidi Chu <i@2333.moe>
Reviewed-By: James M Snell <jasnell@gmail.com>