CI: Helm chart publishing still broken

[trevorwhitney]

#14799 fixed the helm-ci action, allowing helm PRs to be merged. However, publishing releases is still broken:

• https://github.com/grafana/loki/actions/runs/11727098884/job/32667387047
• https://github.com/grafana/loki/actions/runs/11728642157/job/32672566084

Run helm push "/home/runner/work/loki/loki/.cr-release-packages/loki-6.19.0.tgz" "oci://ghcr.io/${GITHUB_REPOSITORY_OWNER}/helm-charts"
  helm push "/home/runner/work/loki/loki/.cr-release-packages/loki-6.19.0.tgz" "oci://ghcr.io/${GITHUB_REPOSITORY_OWNER}/helm-charts"
  shell: /usr/bin/bash -e {0}
  env:
    CR_CONFIGFILE: /home/runner/work/loki/loki/source/production/helm/cr.yaml
    CT_CONFIGFILE: /home/runner/work/loki/loki/source/production/helm/ct.yaml
    CR_INDEX_PATH: /home/runner/work/loki/loki/.cr-index
    CR_PACKAGE_PATH: /home/runner/work/loki/loki/.cr-release-packages
    CR_TOOL_PATH: /home/runner/work/loki/loki/.cr-tool
    HELM_TAG_PREFIX: helm
    github_app_id: ***
    AUTHTOKEN: ***
Error: unexpected status from POST request to https://ghcr.io/v[2](https://github.com/grafana/loki/actions/runs/11727098884/job/32667387047#step:18:2)/grafana/helm-charts/loki/blobs/uploads/: 403 Forbidden
Error: Process completed with exit code 1.

Last successful run was 3 weeks ago: https://github.com/grafana/loki/actions/runs/11374046600

[trevorwhitney]

@morganrowse if you're still interested, looks like the saga isn't quite over