Remove metrics mTLS exception

For https://repo1.dso.mil/platform-one/big-bang/bigbang/-/issues/1310

chart/templates/bigbang/peerauthentication/vault-metrics-exception.yaml

-{{- if and .Values.istio.enabled (eq .Values.istio.mtls.mode "STRICT") }}
-apiVersion: "security.istio.io/v1beta1"
-kind: PeerAuthentication
-metadata:
-  name: vault-metrics-exception
-  namespace: {{ .Release.Namespace }}
-spec:
-  mtls:
-    mode: {{ .Values.istio.mtls.mode }}
-  portLevelMtls:
-    "8080":
-      mode: PERMISSIVE
-  selector:
-    matchLabels:
-      app.kubernetes.io/name: vault
-{{- end }}