Istio sidecar NetworkPolicy Addition

Loki is istio injected, but had no istio or istio.enabled value or Istio related NetworkPolicy was included.

chart/templates/bigbang/networkpolicies/allow-sidecar-scraping.yaml

+{{- if and .Values.networkPolicies.enabled .Values.istio.enabled }}
+apiVersion: networking.k8s.io/v1
+kind: NetworkPolicy
+metadata:
+  name: allow-loki-sidecar-scraping
+  namespace: {{ .Release.Namespace }}
+spec:
+  ingress:
+  - from:
+    - namespaceSelector:
+        matchLabels:
+          app.kubernetes.io/name: monitoring
+      podSelector:
+        matchLabels:
+          app: prometheus
+    ports:
+    - port: 15020
+      protocol: TCP
+  podSelector:
+    matchLabels:
+      app: loki
+  policyTypes:
+  - Ingress
+{{- end }}