fix: Remove centralized auth policies, change path to remaining, update docs

General MR

Summary

Cleans up the Istio Authorization Policies

Linked Issue

• 2032
• 2081

Upgrade Notices

N/A

chart/templates/bigbang/authorization-policies/allow-nothing-policy.yaml

-{{- /* the allow-nothing policy should eventually be provided by istio itself cluster-wide */ -}}
-{{- if and .Values.istio.enabled .Values.istio.hardened.enabled -}}
-apiVersion: security.istio.io/v1
-kind: AuthorizationPolicy
-metadata:
-  name: allow-nothing-policy
-  namespace: {{ .Release.Namespace }}
-spec: {}
-{{- end }}
\ No newline at end of file