Remove legacy BO code #1009

Job	Run time
Publish Image (darts-cnn-cifar10-cpu, linux/amd64,linux/arm64, examples/v1beta1/trial-images/dart... / Publish Image	5m 32s
Publish Image (enas-cnn-cifar10-cpu, linux/amd64,linux/arm64, examples/v1beta1/trial-images/enas-... / Publish Image	6m 38s
Publish Image (darts-cnn-cifar10-gpu, linux/amd64, examples/v1beta1/trial-images/darts-cnn-cifar1... / Publish Image	7m 29s
Publish Image (enas-cnn-cifar10-gpu, linux/amd64, examples/v1beta1/trial-images/enas-cnn-cifar10/... / Publish Image	8m 11s
Publish Image (mxnet-mnist, linux/amd64,linux/arm64, examples/v1beta1/trial-images/mxnet-mnist/Do... / Publish Image	5m 1s
Publish Image (pytorch-mnist-cpu, linux/amd64,linux/arm64, examples/v1beta1/trial-images/pytorch-... / Publish Image	5m 2s
Publish Image (pytorch-mnist-gpu, linux/amd64, examples/v1beta1/trial-images/pytorch-mnist/Docker... / Publish Image	7m 21s
Publish Image (simple-pbt, linux/amd64,linux/arm64, examples/v1beta1/trial-images/simple-pbt/Dock... / Publish Image	1m 27s
Publish Image (tf-mnist-with-summaries, linux/amd64,linux/arm64, examples/v1beta1/trial-images/tf... / Publish Image	6m 12s
	52m 53s

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