Kubernetes deployment model alignment with documented security concerns

[jmcshane]

In the Indexing docs, it says:

Firewall - Only the Indexer service needs to be exposed publicly and particular attention should be paid to locking down admin ports and database access: the Graph Node JSON-RPC endpoint (default port: 8030), the Indexer management API endpoint (default port: 18000), and the Postgres database endpoint (default port: 5432) should not be exposed.

The service for the query-node uses a NodePort service across all the endpoints:

indexer/k8s/base/query-node/service.yaml

Lines 17 to 18 in 0d10609

	- name: index-node
	port: 8030

This was done in #493 but not explicitly called out in the PR docs why the ports needed to be added to the externally facing service (changed from LoadBalancer to NodePort).