Move images using load/save instead of docker daemon. (#998)

This change is necessary because the docker daemon API has a minimum of
1.24, but buildah and podman use a minimum version of 1.22.

Using the save + load bypasses API issues by using the standard approach
to saving and loading images.

Signed-off-by: Caleb Brown <calebbrown@google.com>

Makefile

@@ -98,7 +98,7 @@ push_prod_images: push_prod_sandboxes push_analysis_image push_scheduler_image
 # pass '-nopull' to scripts/run_analysis.sh
 #
 sync_%_sandbox:
-	sudo buildah pull docker-daemon:${REGISTRY}/${IMAGE_NAME}:$(TAG)
+	docker save ${REGISTRY}/${IMAGE_NAME}:$(TAG) | sudo podman load
 
 sync_dynamic_analysis_sandbox: IMAGE_NAME=dynamic-analysis
 sync_dynamic_analysis_sandbox: build_dynamic_analysis_sandbox