Avoid creating Route 53 zone(s)

## Prerequisites

* [X] I am running the latest version. (`up upgrade`)
* [X] I searched to see if the issue already exists.
* [X] I inspected the verbose debug output with the `-v, --verbose` flag.
* [ ] Are you an Up Pro subscriber?

## Description

Hi, thanks for this awesome tool.
I plan to use it to run a service on a domain whose DNS records are managed in cloudflare.
I see when I setup the stack a new Route 53 zone is created.

I was wondering if this is necessary since I just need to map the cloudfront endpoint to a CNAME record in cloudflare.

Just trying to understand if paying for the zone is really necessary.

Thanks