Having revoke-sudo in the pre playbook of unittest has made us not able
to re-use unittest for javascript, and also means we can't use
nodejs-npm for nodejs-npm-run-test, which is a bit odd.
Instead, add the role to the run playbook for tox and npm, which allows
us to stack and combine things a bit better.
Change-Id: I0c7c508996ad2647db706d4ebf156c5dd96bf9b5
6d8d1a4408