Final steps migration to CNCF infrastructure

[inteon]

This issue tracks the progress of the migration to CNCF infrastructure.

• [x] moved the GCP cert-manager-release project to the CNCF GCP organisation
• [x] clean-room deploy of cert-manager testing infrastructure in new GCP projects
• [x] bug and stability fixes
• [x] via CNCF service desk: point registar to new CloudDNS instances on GCP
• [ ] install triage-party tool (first determine if this tool is still relevant)
• [ ] migrate Netlify
• [ ] tear-down old testing infrastructure (https://github.com/jetstack/terraform-jetstack-build-infra/pull/36)

[maelvls]

~Can we close this ticket? Or do we still need to do something?~

I think we have decided we want to continue using http://triage.infra.cert-manager.io/