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

Start by reproducing the three steps in google-maps.component.html with the corresponding logic in google-maps.component.ts, confirming that centerChanged fires while zoom remains unchanged. Trace the Angular Google Maps binding behavior and verify the fix by ensuring a center update restores the zoom to 17.

Written by the indexing model from the issue text.