tests: Fedora testing does not support `Download an OS`
tests: Fedora testing does not support `Download an OS`

Since it is Fedora 30 with updates-testing repos.

Closes #12977
cockpit-project/cockpit,mvollmer/cockpit,deryni/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,garrett/cockpit,deryni/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,mvollmer/cockpit,cockpituous/cockpit,garrett/cockpit,martinpitt/cockpit,martinpitt/cockpit,deryni/cockpit,deryni/cockpit,deryni/cockpit,martinpitt/cockpit,mvollmer/cockpit,cockpituous/cockpit,garrett/cockpit,cockpituous/cockpit,mvollmer/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,deryni/cockpit,deryni/cockpit,cockpit-project/cockpit,martinpitt/cockpit,garrett/cockpit,cockpit-project/cockpit,garrett/cockpit,cockpituous/cockpit,moraleslazaro/cockpit