jenkins-build: Don't build ceph

Ceph isn't supported on RHEL and make the CI failing.
puppet-master: Using {add|remove}-puppet repository

Makes code more generic and easier to maintain
puppet-master: Don't try to install cloud-init twice

As we have a special function to handle it, let's use it and don't ask
the same packages to be installed twice.
puppet-master: {add|remove}-epel-repo one for all

It wasn't very logical to add epel repository in install_puppet and
never remove it.

This patch make the add and remove at the beginning/end of the
procedure.