bug(google-maps): Zoom not updated on centerChange

### What are you trying to do?

Trying to zoom map after center change:
google-maps.component.html
```

```

google-maps.component.ts
```
export class GoogleMapsComponent {
@Input() center!: google.maps.LatLngLiteral;
zoom = 17;
...

centerChanged() {
console.log('center changed');
this.zoom = 17;
}
```

### What troubleshooting steps have you tried?

Zoom is not changed

### Reproduction

Steps to reproduce:
1. User changes zoom
2. User clicks on marker link that updates center variable.
3. Center is changed, console.log is fired but zoom is not updated

### Environment

- Angular: 12.2.6
- Browser(s): Firefox/Chrome
- Operating System Windows

首先，在 google-maps.component.ts 中使用对应逻辑复现 google-maps.component.html 中的三个步骤，确认 centerChanged 会触发，而 zoom 保持不变。跟踪 Angular Google Maps 的绑定行为，并确保中心更新会将缩放级别恢复为 17，以验证修复。

由索引模型根据 Issue 内容生成。