[s3c] setup skaffold image to pull binary dependencies from known GCS bucket

[aaron-prindle]

Currently the skaffold image pulls binaries directly from the internet during the build process. When selecting the version of each binary to use, we should instead pull them down and store them in a GCS bucket that the build process then pulls from for security and availability. Currently some of the potential security issues are currently mitigated via the checksum values that we look at but migrating these binaries to be pulled from a GCS bucket we host is in our s3c roadmap.