The Bifrost CI job seems quite unstable, often failing while attempting
to reach the public epel package repositories. We shouldn't need to
install any packages when deploying the container - they should all have
been installed in the image already.

This change avoids running the scripts/env-setup.sh script, which is run
when the container image is built.

It also removes sourcing of /opt/stack/ansible/hacking/env-setup, which
is now just a stub.

Change-Id: I1786e5337a397cb7b427d6b87c21eaee600af170