Move remaining use of Tekton-produced images from gcr.io to ghcr.io

[AlanGreene]

Changes

Most images produced by Tekton projects, including tooling built from tektoncd/plumbing, are now consumed from ghcr.io.

The Dashboard E2E base image is now also published to ghcr.io. Update the Dockerfile to include the expected OCI labels. See https://docs.github.com/en/packages/working-with-a-github-packages-registry/working-with-the-container-registry#labelling-container-images for details.

/kind misc

Submitter Checklist

As the author of this PR, please check off the items in this checklist:

• Docs included if any changes are user facing
• Tests included if any functionality added or changed
• Follows the commit message standard
• Meets the Tekton contributor standards (including
  functionality, content, code)
• Has a kind label. You can add one by adding a comment on this PR that contains /kind <type>. Valid types are bug, cleanup, design, documentation, feature, flake, misc, question, tep
• Release notes block below has been updated with any user facing changes (new features, significant UI changes, API changes, bug fixes, changes requiring upgrade notices or deprecation warnings)
• Release notes contains the string "action required" if the change requires additional action from users switching to the new release

Release Notes

NONE

[tekton-robot]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[AlanGreene]

/test all

[briangleeson]

/lgtm

[tekton-robot]

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