The code that enables TLS for Solr and Prometheus exporter pods has evolved over the past several months, and still has some additional changes we want to add (e.g. #300). Let's clean-up the TLS code before adding more features as it's become a bit hard to follow the logic and is infused across too many places. This will also help reduce the size and complexity of the GenerateStatefulSet method in solr_util.go.