Build notification configuration failed with Invalid parameter: Topic Name error

### 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

Notifications

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

While configuring build notification for branch name "build/course", the following error is observed.

Invalid parameter: Topic Name

This is happening as Amplify is trying to create SNS topic in the following format which does not comply with SNS topic naming constraints.

amplify-app-id_build/course

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

Amplify should automatically handle such scenarios.

Start with the Notifications configuration flow and review FAQ.md for existing guidance on build notifications. Reproduce the case using the branch name "build/course", then trace the SNS topic creation path and define completion as successful configuration without an Invalid parameter: Topic Name error.

Written by the indexing model from the issue text.