CI: add tags to match the new shared runners in Inria Gitlab
Some shared runners have been added and should replace the ones from qualif that were used so far, but unfortunately we can't choose only to use the large ones in Gitlab configuration as we did for the qualif ones... So we have to resort to the tags. I like it a bit less (if someone would like to use other runners he would need to define the tag for them) but it is largely hypothetical for the time being.