Change DefaultIndexImage to UBI

[e0ne]

Description of the change: Change untar image from busybox to UBI image as #5191

Motivation for the change: Remove dependency on dockerhub

Checklist

If the pull request includes user-facing changes, extra documentation is required:

• [ ] Add a new changelog fragment in changelog/fragments (see changelog/fragments/00-template.yaml)
• [x] Add or update relevant sections of the docs website in website/content/en/docs