bots: Fix triggered tests for openshift image refreshes
bots: Fix triggered tests for openshift image refreshes

OpenShift tests don't run on fedora-30 any more, as cockpit-kubernetes
is not packaged there. Run rhel-7-7 instead.

Closes #12073
martinpitt/cockpit,moraleslazaro/cockpit,deryni/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,mvollmer/cockpit,martinpitt/cockpit,cockpit-project/cockpit,garrett/cockpit,garrett/cockpit,martinpitt/cockpit,cockpit-project/cockpit,cockpituous/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,cockpit-project/cockpit,garrett/cockpit,martinpitt/cockpit,garrett/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,cockpit-project/cockpit,deryni/cockpit,moraleslazaro/cockpit,mvollmer/cockpit,deryni/cockpit,mvollmer/cockpit,deryni/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,deryni/cockpit,cockpituous/cockpit,garrett/cockpit,deryni/cockpit,deryni/cockpit