CVE-2021-4200: Write access to the Catalog for any user when restricted-admin role is enabled

### Impact This vulnerability only affects customers using the [`restricted-admin`](https://rancher.com/docs/rancher/v2.6/en/admin-settings/rbac/global-permissions/#restricted-admin) role in Rancher. For this role to be active, Rancher must be bootstrapped with the environment variable `CATTLE_RESTRICTED_DEFAULT_ADMIN=true` or the configuration flag `restrictedAdmin=true`. A flaw was discovered in Rancher versions from 2.5.0 up to and including 2.5.12 and from 2.6.0 up to and including 2.6.3 where the `global-data` role in `cattle-global-data` namespace grants write access to the Catalogs. Since each user with any level of catalog access was bound to the `global-data` role, this grants write access to templates (`CatalogTemplates`) and template versions (`CatalogTemplateVersions`) for any user with any level of catalog access. New users created in Rancher are by default assigned to the `user` role (standard user), which is not designed to grant write catalog access. This vulnerabilit...