Allows helm to upgrade Istio from 1.4 to 1.5
Several resources that were created by Istio components in <= 1.4.x were then added to the 1.5 manifests which causes a helm error. This removes them so they can be added by the new 1.5 helm charts.
Be aware there are complications with this approach, for instance removal of the istio-reader-service-account will remove its secrets and break various multi-cluster installations.
See the original issue for more information: istio/istio#21648