Fix up helm tests

Author: JohnGarbutt

chart/tests/__snapshot__/snapshot_test.yaml.snap

@@ -5705,7 +5705,7 @@ templated manifests should match snapshot:
                 severity: warning
             - alert: AzimuthKubernetesNgnixIngressNotRemoved
               annotations:
-                description: Kubernetes cluster {{ $labels.cluster_namespace }}/{{ $labels.cluster_name }} still has ngnix-ingress deployed.
+                description: Kubernetes cluster {{ $labels.cluster_namespace }}/{{ $labels.cluster_name }} still has nginx-ingress deployed.
                 summary: Kubernetes cluster still has nginx-ingress deployed.
               expr: sum(azimuth_kube_cluster_addon_phase{addon="ingress-nginx"}) by(cluster_namespace, cluster_name) > 0
               for: 5m