[335] - Istio specific labels and mTLS support

Following Elastic's guide to using istio with ECK + operator since configuration has been updated since we last updated.

https://www.elastic.co/guide/en/cloud-on-k8s/current/k8s-service-mesh-istio.html

• Migrating to using istio mTLS to handle SSL connection between communication to Elasticsearch.
• Adding more labels to work nicer with istio service mesh.

Opened in relation to https://repo1.dso.mil/platform-one/big-bang/bigbang/-/issues/335