containers/ws: Drop installation from preview COPR
containers/ws: Drop installation from preview COPR

This is a bit questionable, and was only done to get a synchronous
upstream and container release. But we haven't done the latter for some
time since moving to packit, and it's not really necessary to be
synchronous as long as it's automated.

Let's rather build from pure Fedora.

cockpit-project/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,cockpit-project/cockpit