DNS problem with branches with very long names

**Describe the bug**
Branches with very long names are assigned invalid DNS names, so when you try to access the connected branch, you get the error:

```
This site can’t be reached
(branch name)’s server IP address could not be found.
```

This is because the label part for the branch name is longer than 63 characters. According to [RFC1035](https://tools.ietf.org/html/rfc1035):

```
The labels must follow the rules for ARPANET host names. They must
start with a letter, end with a letter or digit, and have as interior
characters only letters, digits, and hyphen. There are also some
restrictions on the length. Labels must be 63 characters or less.
```

**To Reproduce**
Steps to reproduce the behavior:
1. Go to https://feature-fpafe-6-when-the-user-logs-in-if-the-password-is-about-to-expire-display-a-countdown-or-if.d1m2p9ror6ta9m.amplifyapp.com/
4. See error

This branch is properly connected and built in the AWS Amplify Console. The problem occurs with both auto connected and manually connected branches.

**Expected behavior**
The connected branch should be assigned the following domain name:

https://feature-fpafe-6-when-the-user-logs-in-if-the-password-is-about.d1m2p9ror6ta9m.amplifyapp.com

which is a valid DNS name.

The issue names no files, tests, or entry points. Start by locating the code that converts connected branch names into Amplify-hosted DNS labels, then verify the generated label stays within the 63-character DNS limit while preserving the expected shortened hostname.

Written by the indexing model from the issue text.