Improve loki log labels

WARNING: we must be exceedingly careful with cardinality with loki log labels, just like prometheus, high cardinality ruins your performance. No random strings in labels beyond the invoker. (job)

Currently a very limited set of labels, we would like more to allow teams to efficiently search across their logs. A good addition would be namespace, but only non-random namespaces. openshift-* would be a logical restriction we could maek to the promtail config.