Harness tests should be checked in CI

[Ms2ger]

#4468 broke test/harness/verifyProperty-value-error.js (see #4493), but CI was all green. We should fix that.

[ptomato]

Since the harness tests don't depend on any implementation specifics, we could create a job that runs them in whatever version of Node is installed, and fail the PR if any harness tests fail.