test: fix tests that check error messages

20285ad1 changed the format
of error messages throughout lib. However, the tests were not
updated to reflect these changes. This commit makes those
changes.

PR-URL: https://github.com/nodejs/node/pull/3727


Reviewed-By: Roman Reiss <me@silverwind.io>
Reviewed-By: Johan Bergström <bugs@bergstroem.nu>
Reviewed-By: James M Snell <jasnell@gmail.com>