Add containerd IPv6 env vars

[taylorsilva]

Why do we need this PR?

Adding env vars from https://github.com/concourse/concourse/pull/8801

Contributor Checklist

• [ ] ~Variables are documented in the README.md~ Not applicable for env vars
• [x] Which branch are you merging into?
  • master is for changes related to the current release of the concourse/concourse:latest image and should be good to publish immediately
  • dev is for changes related to the next release of Concourse (aka unpublished code on master in concourse/concourse)

Reviewer Checklist

This section is intended for the core maintainers only, to track review progress. Please do not fill out this section.

• [ ] Code reviewed
• [ ] Topgun tests run
• [ ] ~Back-port if needed~
• [x] Is the correct branch targeted? (master or dev)