Did you ever get this working with v2.2.4? I have upgraded to v2.2.6 and am still struggling to see the helm charts update when previewing after updating them in my Custom Catalog Repo (Amazon S3) and performing a catalog refresh. I have actually opened a new issue that is specific to clearing the catalog-cache.
If I can’t disable it, I am probably going to have to clear the catalog-cache directory inside the rancher containers prior to each deployment (and refresh catalog) to ensure I deploy the most up-to-date helm charts.