Migrate away from gcr.io/k8s-testimages repo

[BenTheElder]

/kind bug
/priority important-soon
kubernetes/k8s.io#1523

gcr.io/k8s-testimages is a legacy Google-owned GCR/AR repo. We should migrate to a community-owned AR registry.

See for example kubernetes/k8s.io#1523 (comment)

https://cs.k8s.io/?q=k8s-testimages&i=nope&literal=nope&files=&excludeFiles=&repos=kubernetes/test-infra

[BenTheElder]

/sig testing

[BenTheElder]

@kubernetes/sig-k8s-infra-leads I think we will need an image build for logexporter/ (in this repo) both for this one and for kubernetes/perf-tests#3376

It should probably be a
/sig scalability
staging project

[BenTheElder]

A number of the image builds are also still configured to stage in gs://k8s-testimages-scratch