title: issue when upgrading agic to 1.5.2
body: <p>As our aks relate to two different agw, when upgrading AGIC by helm, we got this error:</p>
  <p>helm upgrade agic-ass application-gateway-kubernetes-ingress/ingress-azure --version 1.5.1
  Error: UPGRADE FAILED: rendered manifests contain a resource that already exists. Unable to continue with update: IngressClass &quot;azure-application-gateway&quot; in namespace &quot;&quot; exists and cannot be imported into the current release: invalid ownership metadata; label validation error: missing key &quot;app.kubernetes.io/managed-by&quot;: must be set to &quot;Helm&quot;; annotation validation error: missing key &quot;meta.helm.sh/release-name&quot;: must be set to &quot;agic-ass&quot;; annotation validation error: missing key &quot;meta.helm.sh/release-namespace&quot;: must be set to &quot;default&quot;</p>
  <p>how to fix it and upgrade AGIC to 1.5.1 by helm?</p>