partitioned_update: use namespaced service name when running in a separate namespace

[neurodrone]

In order to decide the service name to reach out for establishing connection, currently, we check whether we run within Kubernetes or outside of it. In order to account for the edge case mentioned in https://github.com/cockroachdb/cockroach-operator/issues/906, when we see the Operator is running within the same Kubernetes cluster, we additionally check if its within the same namespace as the managed clusters or not.

Fixes https://github.com/cockroachdb/cockroach-operator/issues/906.