OptaWeb employee-rostering frontend is unable to find node.exe for Windows tests

Jenkins jobs for Windows weren't run because of employee-rostering frontend, with node version v8.12.0, couldn't find node.exe in repo. This file is present in v11.6.0 repo.

The issue has been potentially resolved with https://github.com/kiegroup/optaweb-employee-rostering/pull/355 and should be no more for the CR2 build.