nz-modal when nzOnOk is typeof OnClickCallback<any>, click ok button trigger nzAfterClose twice

[tky753]

Reproduction link

https://stackblitz.com/edit/ng-zorro-antd-modal-bug-report000?file=src%2Fapp%2Fapp.component.ts

Steps to reproduce

1. open console
2. click show modal button
3. click 确定 button.

handleOk(): boolean {
  return true;
}

handleCancel(): boolean {
  return undefined;
}
afterClose($event: any){
  console.log('closed for: '   $event);
}

What is expected?

console one line:
closed for: true

What is actually happening?

console two lines:
closed for: true
closed for: undefined

Environment	Info
ng-zorro-antd	7.3.3
Browser	Chrome 72.0.3626.121（正式版本） （64 位

---

BTW, when opening the page, afterClose is triggered once immediately.

[hsuanxyz]

fixed via #4702