update docs to reflect our latest understanding of `ingress-nginx` upgrades.

update docs ([here](https://github.com/DataONEorg/k8s-cluster/blob/main/control-plane/control-plane.md#Ingress-Controller) and anywhere else) to reflect our latest understanding of `ingress-nginx` upgrades. Specifically, we no longer use the TCP nodeports for solr etc. What else?