Open in order to backport this work: https://github.com/openshift/cluster-node-tuning-operator/pull/936 to 4.15

This is needed since the MixedCPUs feature is part of 4.15 payload and we need to have the e2e test there as well in order to make sure the feature is in a good shape and none regression is happening.

The tests themselves would not affect the payload though.