ovirt-engine Ci is very very slow - hard to merge patches

As you probably know the CI jobs for ovirt engine takes ages. After it completes, you need to pray that the tree didn't change otherwise gerrit refuse to merge and we over it again. Please disable it for now on *master* as we can't merge quick enough. Stable branches doesn't change that often so its a win. We don't risk them and they anyhow makes less noise. Thanks, Roy