test: simplify common.expectsError

The mustCall is actually only necessary in case it is used as
callback. Otherwise it works as a must call on its own.

PR-URL: https://github.com/nodejs/node/pull/17616


Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>