test: cleanup test-util-inherits.js

Replaced constructor with regular expression for assert.throw().

PR-URL: https://github.com/nodejs/node/pull/12602


Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>