Fix explorer previews caused by Helm 2 deprecation

error: failed to add chart repositories: failed to add the Helm repository with URL 'https://storage.googleapis.com/chartmuseum.jenkins-x.io': failed to add the repository 'storage.googleapis.com' with URL 'https://storage.googleapis.com/chartmuseum.jenkins-x.io': failed to run 'helm repo add storage.googleapis.com https://storage.googleapis.com/chartmuseum.jenkins-x.io' command in directory '.', output: 'Error: Couldn't load repositories file (/root/.helm/repository/repositories.yaml).