DodoApp: Use untrusted-external runtime class for app runner

Change-Id: I6beab523e1688fc98c2b6a5b756f46a5fc89f3cb
diff --git a/charts/app-runner/templates/install.yaml b/charts/app-runner/templates/install.yaml
index d05287d..acd0b3d 100644
--- a/charts/app-runner/templates/install.yaml
+++ b/charts/app-runner/templates/install.yaml
@@ -61,6 +61,7 @@
       labels:
         app: app-app
     spec:
+      runtimeClassName: {{ .Values.runtimeClassName }}
       volumes:
       - name: ssh-key
         secret: