private void configActivationListenersOnRemove(ApplicationId applicationId) {
        hostRegistry.removeHosts(applicationId);
        configActivationListener.applicationRemoved(applicationId);
    }
Activates the config of the given app. Notifies listeners

@param applicationVersions the {@link ApplicationVersions} to be activated
configserver/src/main/java/com/yahoo/vespa/config/server/application/TenantApplications.java