create individual services for MGMs
Just like !45 (merged) , this creates individual services for each MGM member in the statefulset.
fixes #75 (closed) (at last!!!)
This also moves the default value of MGM replicaCount (1) to values.yaml to avoid specifying it redundantly in multiple places.
Purpose:
- for #88 , it opens the way to the eventual possibility of having multiple MGM statefulset members and allows each one to be individually addressed from outside the cluster with Loadbalancer services
- works around a very long-standing class of Helm bugs about values handling in sub-charts that are blocking !49 from addressing external access to MGM
- details. Helm devs are trying to address this with some proposals/ideas for a new major version Helm 4