As CI images have pre-installed latest virtualenv package wich breaks
deployments. This will ensure that this package will be dropped and
appropriate one will be installed later.
This also makes ubuntu use appropriate python3 venv tooling and
drops py2 packages installation
Additionally virtualenv is dropped from requirements and ubuntu
upgrade jobs is marked as non-voting until backporting change
to previous release
Change-Id: I50931e0f68176bbaebfb68eec9f84241816c7fe3
3800754c1f