We need venv on slaves only in case of run_tests roles
We need venv on slaves only in case of run_tests roles

We don't need venv for building iso. venv should be used
only in case of run_test roles.

Change-Id: I6a82e0d7aaddef4496a46fdb94b8c6647e53f71a

fuel-infra/puppet-manifests,fuel-infra/puppet-manifests,fuel-infra/puppet-manifests,fuel-infra/puppet-manifests