[Authenticator] Incorrect message for user pools with disabled self registration

### Before creating a new issue, please confirm:

- [x] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-ui-android/issues?q=is%3Aissue+).
- [x] I have read the guide for [submitting bug reports](https://github.com/aws-amplify/amplify-ui-android/blob/main/CONTRIBUTING.md#reporting-bugsfeature-requests).

### Which UI component?

Authenticator

### Gradle script dependencies

```kotlin
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```

### Environment information

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### Please include any relevant guides or documentation you're referencing

_No response_

### Describe the bug

If the User Pool has disabled self registration then sign ups will fail. The error message shown when this happens says that password cannot be reset in this state - this is nonsensical.

### Reproduction steps (if applicable)

1. Disable self registration in user pool
2. Attempt to create an account via Authenticator
3. Observe snackbar message

### Code Snippet

```kotlin
// Put your code below this line.

```

### Log output

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```

### Configuration File

_No response_

### Additional information and screenshots

_No response_

Start with the Authenticator sign-up flow and reproduce the issue using an AWS user pool with self registration disabled. Trace the snackbar message shown after account creation fails and verify that the resulting message describes the disabled-registration condition rather than password reset.

Written by the indexing model from the issue text.