Update builder base image
Update builder base image

This image seems to be more publicly advertised compared to the one currently used, even though the latter is also from Google.

See: https://cloud.google.com/container-registry/docs/managed-base-images#available_images

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=242666510

google/nomulus,google/nomulus,google/nomulus,google/nomulus,google/nomulus,google/nomulus