Originally from:
https://github.com/GoogleCloudPlatform/k8s-metadata-proxy/tree/master/test

Moving the code here to prevent bit-rot and to be sure we can recreate
or update the images on demand. Moving it here also ensures we can use
the common harness to build the multi-arch manifests needed for running
the metadata concealment e2e test can run on multiple architectures.

Change-Id: I15009268da4e7809a1c03d9af3181b585afa8139