We want to trigger ansible runs on bridge.o.o from zuul jobs. First
iteration of this tried to login as root but this is not allowed by our
ssh config. That config seems reasonable so we add a zuul user instead
which we can ssh in as then run things as root from zuul jobs. This
makes use of our existing user management system.
Change-Id: I257ebb6ffbade4eb645a08d3602a7024069e60b3