Amplify CI/CD stops working after changed username in Github; Cannot Reauthorize

### 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 read the guide for [submitting bug reports](https://github.com/aws-amplify/amplify-hosting/blob/master/CONTRIBUTING.md).
- [X] I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.
- [X] I have removed any sensitive information from my code snippets and submission.

### App Id

d2snwrnsheyx6w

### AWS Region

us-east-1

### Amplify Hosting feature

Access control

### Describe the bug

After updating my github username, I cannot reconnect the main branch of my repository.

I created a new branch. This branch connected and deployed with no problems. However, I would like my deployment to come from "main".

The repository is still connected to "/old_username/repo_name".

I have read [issue #2493](https://github.com/aws-amplify/amplify-hosting/issues/2493). However, I cannot grant permission to access this repository to AWS Amplify through Github.

### Expected behavior

I expected CI/CD of pushed code.

### Reproduction steps

1. Change GH Username
2. navigate to the Amplify console -> App Settings -> General -> Reconnect repository
3. Click "Configure GitHub App" and update settings to give permission to access target repository
4. Reach error saying "We do not have permission to access this repository. Please update your permissions and try again."
5.

### Build Settings

_No response_

### Log output

```
# Put your logs below this line

```

### Additional information

_No response_

Start with the Amplify console flow at App Settings → General → Reconnect repository, then Configure GitHub App, and reproduce the failure after changing the GitHub username. Check the repository permission and reauthorization behavior; done means the main branch reconnects and pushed code triggers CI/CD deployment.

Written by the indexing model from the issue text.