doc,test: remove unnecessary await with return instances

Remove unnecessary `await` in combination with `return` in preparation
for enabling lint rule.

PR-URL: https://github.com/nodejs/node/pull/17265


Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>