The check-markdown tool gets called as part of a TC build. The
configure action in `build.sh` will select the correct node version
and set the necessary environment variables. However, previously this
failed because `${KEYMAN_ROOT}/node_modules` might already exist even
though we didn't configure check-markdown before.
This change checks a local directory as output of the configure action
and thus allows to build on a Noble based TC agent.
