Add Ubuntu-based runner-helper image

What does this MR do?

Adds a ubuntu-based runner-helper image.

Why was this MR needed?

Our alpine-based image has known DNS issues.

What's the best way to test this MR?

There's several parts to this MR:

• Building both the ubuntu and alpine flavored images:

  make helper-dockerarchive-host

• Manual running based on the helper_image_flavor.

  Default:

    [runners.docker]
      helper_image_flavor = ""

  Alpine specifically specified:

    [runners.docker]
      helper_image_flavor = "alpine"

  Ubuntu:

    [runners.docker]
      helper_image_flavor = "ubuntu"

  Image tags are x86_64-{revision} for alpine, to maintain backwards compatibility. For ubuntu, they're ubuntu-x86_64-{revision}. The preloaded images we create that sit on the disk always contain the flavor name.

• Publishing images to the repositories

  With PUBLISH_IMAGES temporary enabled, the pipeline successfully pushed ubuntu and default/alpine flavored images: https://gitlab.com/gitlab-org/gitlab-runner/-/jobs/1238128010#L1761

What are the relevant issue numbers?

Closes #26876 (closed) Closes #4129 (closed)