Mailchimp block: Subscribing with an unsubbed address results in error / failure

### Impacted plugin

Jetpack

### Steps to Reproduce

1. Make sure you have a WP site connected to a valid Mailchimp account and list.
2. Add a Mailchimp block to any page.
3. Subscribe to the list with the block.
4. Unsubscribe.
5. Try to subscribe again with the same email address.
6. Note that this is the error you see:

Checking the Network tab of the dev tools this is what I see:

```
{
"error": "member_in_compliance_state",
"message": "Mailchimp Error: EMAIL ADDRESS is in a compliance state due to unsubscribe, bounce, or compliance review and cannot be subscribed."
}
```

### A clear and concise description of what you expected to happen.

The user should be subscribed to the list again. This is properly managed with Gravity Forms and with MC4WP.

If it's not possible to update our Mailchimp block integration to allow unsubbed subscribers to resubscribed, then the error messaging should indicate that in a user-friendly way. Something like:

> Because you have previously unsubscribed from this Mailchimp list, we're not able to subscribe you here again. Please contact the site owner directly and they can help you to subscribe again.

### What actually happened

The error I see confused me as to why I'm not able to subscribe.

### Other information

_No response_

### Operating System

macOS

### OS Version

_No response_

### Browser

Chrome/Chromium, Firefox, Safari

### Browser Version(s)

_No response_

Start with the Jetpack Mailchimp block integration and reproduce the unsubscribe/resubscribe flow while inspecting the Network request. Done means either the previously unsubscribed address can subscribe again or the block shows a clear, user-friendly explanation of why Mailchimp rejects it.

Written by the indexing model from the issue text.