[Bug]: KV database gets emptied after linking GitHub repo to deployctl-deployed project

### Problem description

I've encountered a problem where the main KV database of my Deno Deploy project becomes empty after I link it to a GitHub repository. This happens when the project was initially deployed using `deployctl` and had data in its KV database *before* linking to GitHub. It seems like the data might be moved to the preview database instead of staying in the main one.

### Steps to reproduce

1. Deploy a project to Deno Deploy using `deployctl`.
2. Store some data in the project's Deno KV database.
3. Go to the Deno Deploy dashboard for your project and link it to a GitHub repository. When you link, choose the option "Just link the repo, I’ll set up GitHub Actions myself" or set the entrypoint and deploy.
4. After the deployment , check the main KV database for your project. You'll find it's empty.
5. (Optional) Check the preview KV database – you might find your data there.

### Expected behavior

Linking a GitHub repository to a project that was initially deployed with `deployctl` and already using the main KV database should *not* empty the main KV database. I expected the data to remain in the main KV database even after switching to GitHub Actions deployments.

### Environment

Deno-version : 2.1.9
deployctl-version : 1.13.0

### Possible solution

Clear Warning and Documentation If this behavior is intended
Automatic Data Migration option

Could you please investigate this issue and see if this is the intended behavior or a bug?