Stop generating new CNAMES everytime SSL Configuration fails

### Before opening, please confirm:

- [X] I have checked to see if my question is addressed in the [FAQ](https://github.com/aws-amplify/amplify-hosting/blob/master/FAQ.md).
- [X] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-hosting/issues?q=is%3Aissue+).
- [X] I have removed any sensitive information from my code snippets and submission.

### Amplify Hosting feature

Not Applicable

### Is your feature request related to a problem? Please describe:

N/A

### Describe how you'd like this feature to work

In a corporate environment, we have a team that manages all the DNS records. Our request can sit for days until its handled and by the time our ticket is looked at, our CNAME records change once we hit retry for the DNS re-check. We submit another DNS request to our internal team, by the time they change the DNS entry, our CNAME is once again different... STOP CHANGING THE CNAME!!!! Let us retry the DNS check WITHOUT CHANGING THE CNAME.

Start by tracing the Amplify Hosting SSL configuration retry flow and its DNS/CNAME validation entry point. Confirm where a retry currently regenerates the CNAME; done means a DNS re-check preserves the existing CNAME and validates the requested certificate. No repository file or test is named in the issue.

Written by the indexing model from the issue text.