Invalid URLs in notification emails sent by Amplify Console

AWS notifications send incorrect URL for build URLs.

I have a branch named `feature/my_CoolBranch`, the build URL for in Amplify Console is therefore:
`https://feature-my-coolbranch..amplifyapp.com`.

However, the URL in the email notification is corrupt and the same branch reads
`https://feature/my_CoolBranch..amplifyapp.com`

I'd expect the URL in the email to match the valid URL as shown in the Console UI.

This can be consistently replicated with any branch name containing underscore `_`, slash `/`. In addition the case should be normalised, i. e. lowercased.

Start at the Amplify Console email notification path that constructs build URLs and compare it with the URL format shown in the Console UI. Reproduce the issue using branch names containing underscores, slashes, and uppercase letters. Done means notification URLs are valid and match the Console URL, including normalized lowercase branch names.

Written by the indexing model from the issue text.