backport to 1.15: http: fix datadog and squash handling of responses without body (#13328)#14458

alyssawilk merged 4 commits intoenvoyproxy:release/v1.15envoyproxy/envoy:release/v1.15from

cpakulski:rel1.15/13328cpakulski/envoy:rel1.15/13328Copy head branch name to clipboard