fix: ai gateway mutating webhook should default failurePolicy to Fail (envoyproxy#1494)

**Description**


-  ai gateway mutating webhook should default failurePolicy to Fail

**Related Issues/PRs (if applicable)**

fixes: envoyproxy#1493

**Special notes for reviewers (if applicable)**

Signed-off-by: googs1025 <[email protected]>

Author: googs1025

manifests/charts/ai-gateway-helm/templates/admission_webhook.yaml

@@ -30,7 +30,7 @@ webhooks:
     sideEffects: None
     admissionReviewVersions: ["v1"]
     timeoutSeconds: 10
-    failurePolicy: Ignore
+    failurePolicy: Fail
 ---
 {{- if .Values.controller.mutatingWebhook.certManager.enable }}
 apiVersion: cert-manager.io/v1