bots: Add libvirt-dbus to rhel-7-7 image
bots: Add libvirt-dbus to rhel-7-7 image

This exists in extras now, and we want to use it.

Preparation for https://bugzilla.redhat.com/show_bug.cgi?id=1712911

Closes #11907

moraleslazaro/cockpit,garrett/cockpit,mvollmer/cockpit,deryni/cockpit,garrett/cockpit,martinpitt/cockpit,deryni/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,deryni/cockpit,cockpit-project/cockpit,moraleslazaro/cockpit,deryni/cockpit,cockpituous/cockpit,moraleslazaro/cockpit,cockpituous/cockpit,martinpitt/cockpit,garrett/cockpit,cockpit-project/cockpit,deryni/cockpit,mvollmer/cockpit,cockpituous/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,garrett/cockpit,cockpituous/cockpit,cockpituous/cockpit,deryni/cockpit,cockpit-project/cockpit,martinpitt/cockpit,mvollmer/cockpit,cockpit-project/cockpit,cockpituous/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,garrett/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,deryni/cockpit,cockpit-project/cockpit