Fix failing upgrade/diff check (+imageBuilderType)

Author: manics

testing/k8s-binder-k8s-hub/binderhub-chart-config-old.yaml

@@ -25,7 +25,7 @@ ingress:
 # against which we haven't. We currently only test this via
 # lint-and-validate-values.yaml that makes sure our rendered templates are
 # valid against a k8s api-server.
-imageBuilderType: "local"
+imageBuilderType: host
 
 # NOTE: This is a mirror of the jupyterhub section in
 #       jupyterhub-chart-config.yaml in testing/local-binder-k8s-hub, keep these