fix(logging): re-enable istio in logging namespace by default, source...

fix(logging): re-enable istio in logging namespace by default, source istio.enabled from passthrough values instead of adding more to the bigbang spec

chart/templates/logging/elasticsearch-kibana/namespace.yaml

 {{- if or .Values.logging.enabled .Values.clusterAuditor.enabled }}
+{{- /* Default to istio being turned on, but disable if user sets istio to disable in the custom passthrough values.
+We have to do it this way because ownership of "istio.enabled" is owned by the chart but also BigBang.  Sourcing values from the passthrough values also means
+  we get to simplify the api space of BigBang just a little bit more.
+*/ -}}
+{{- $istio := .Values.logging.values.istio | default dict }}
+{{- $istioInjection := "enabled" }}
+{{- if and (hasKey $istio "enabled") (not $istio.enabled) }}
+{{- $istioInjection = "disabled" }}
+{{- end }}
 ---
 apiVersion: v1
 kind: Namespace
@@ -8,6 +17,7 @@ metadata:
     app.kubernetes.io/name: logging
     app.kubernetes.io/component: "core"
     {{- include "commonLabels" . | nindent 4}}
+    istio-injection: {{ $istioInjection }}
 ---
 {{- if ( include "imagePullSecret" . ) }}
 apiVersion: v1