Currently the devel packages are installed everywhere,
but they only need to be where the wheels are built.
Also, there is already a task to install the packages
needed on the target hosts when installing - so we do
not need to give the same list to the venv install role
because they will already have been installed.
Change-Id: Ifdff299a81cbba90cf819c9a628650c8b1be3d6a