Remove nessus from cluster configuration

Remove all nessus references: ArgoCD project destination, Istio ambient
enrollment, waypoint gateway, authorization policies, ext-authz policy,
TLS certificate, ingress gateway host, Kyverno exclusion, and Authentik
forward-auth blueprint.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

infrastructure/istio/manifests/apps/authorization-policies-apps.yaml

@@ -273,30 +273,6 @@ spec:
             ipBlocks:
               - "10.244.0.0/16"
 
----
-# --- Nessus: Allow ingress + Prometheus + intra-namespace ---
-apiVersion: security.istio.io/v1
-kind: AuthorizationPolicy
-metadata:
-  name: allow-nessus-access
-  namespace: nessus
-spec:
-  action: ALLOW
-  rules:
-    # Intra-namespace
-    - from:
-        - source:
-            namespaces:
-              - nessus
-    - from:
-        - source:
-            namespaces:
-              - istio-system
-    - from:
-        - source:
-            namespaces:
-              - prometheus
-
 ---
 # --- Rancher: Allow ingress + Prometheus + intra-namespace ---
 apiVersion: security.istio.io/v1