(PE-5594) Stop ring-middleware from truncating gzipped responses

This PR ensures that the `:decompress-body` option will always be false on the request made by `wrap-proxy` after creating the proxied URI. `:decompress-body` defaults to true, and when true, a gzipped response returned by the proxy target would be truncated when returned to the client making the proxy request.
It might be worth adding a comment above this line, I'm not sure it's 100% intuitive why you'd want to do this.