AMPLIFY_DIFF_DEPLOY is no working when new Branch connect

### Before opening, please confirm:

- [X] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-js/issues?q=is%3Aissue+) and [discussions](https://github.com/aws-amplify/amplify-js/discussions).
- [X] I have read the guide for [submitting bug reports](https://github.com/aws-amplify/amplify-js/blob/main/CONTRIBUTING.md#bug-reports).
- [X] I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.

### JavaScript Framework

React

### Amplify APIs

Not applicable

### Amplify Categories

Not applicable

### Environment information

### Describe the bug

AMPLIFY_DIFF_DEPLOY is no working when new Branch connect and build.

AMPLIFY_DIFF_DEPLOY is very nice.

https://docs.aws.amazon.com/ja_jp/amplify/latest/userguide/build-settings.html

### Expected behavior

I think console should deploy front end when AMPLIFY_DIFF_DEPLOY is true and new Branch connect(no frontend hosting).

AMPLIFY_DIFF_BACKEND is no problem.

### Reproduction steps

**Step**

In Amplify Console(web)

1. **build environment** set AMPLIFY_DIFF_DEPLOY is true
2. **Frontend environments->Frontend** connected New Brunch and build.

**Result**
Frontend building is skipped.

### Code Snippet

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

```

### Log output

```
// Put your logs below this line

```

### aws-exports.js

_No response_

### Manual configuration

_No response_

### Additional configuration

_No response_

### Mobile Device

_No response_

### Mobile Operating System

_No response_

### Mobile Browser

_No response_

### Mobile Browser Version

_No response_

### Additional information and screenshots

_No response_

Start in the Amplify Console build environment and review the linked Amplify build-settings documentation. Reproduce the issue with AMPLIFY_DIFF_DEPLOY=true, then compare a newly connected branch with an existing frontend environment. Done means the new branch's frontend build is not skipped while AMPLIFY_DIFF_BACKEND continues to work as reported.

Written by the indexing model from the issue text.