Google Container Registry (GCR) to Artifact Registry (AR) migration outage

[spowelljr]

We were previously on GCR, which is getting shut down (link), so on August 27th I started the migration process to AR. I routed 100% of the traffic to AR and everything seemed fine.

Then on the 28th I noticed that our registry addon tests started to fail (link) since the migration, so I routed 99% of traffic back to GCR and 1% to AR. However, it seems that traffic routed to GCR results in pull errors due to unauthorized errors.

On the 29th I saw reports from users that they were experiencing pull issues and saw the same on our CI, I routed 100% of traffic back to AR. All image pull issues should now be resolved. I'll follow up internally to figure out what happened.