run the "upgrade from last release" pipeline for merge requests

Currently we're testing upgrade between sylva-release in nightly pipelines. Starting from sylva 1.1.0 we commit to provide upgrade to upcoming release in order to be sure that new piece of code wouldn't break the ability to upgrade, we could add an upgrade pipepeline in each merge request in order not to consume too many resources on capo ci, the proposal would be to it for each MR before merge on libvirt metal

cc @loic.nicolle @mederic.deverdilhac @tmmorin @feleouet @e-wyckens