Backport of build: ensure we pull through the hashicorp proxy instead of going directly to the docker hub into release/1.15.x#19484

hc-github-team-consul-core merged 1 commit intorelease/1.15.xhashicorp/consul:release/1.15.xfrom

backport/rboyer/fix-docker-build-rate-limit/widely-stirred-iguanahashicorp/consul:backport/rboyer/fix-docker-build-rate-limit/widely-stirred-iguanaCopy head branch name to clipboard