mobile_builds configuration does not apply to /mobile_guide/

### Steps to reproduce

Following https://github.com/vector-im/element-web/blob/develop/docs/config.md#desktop_builds-and-mobile_builds I have

```
{
"mobile_builds": {
"android": null,
"fdroid": null,
"ios": "https://apps.apple.com/de/app/myapp/id123456789"
}
}
```

in my config.json.

### Outcome

#### What did you expect?

I expected the links on https://element.mydomain.com/mobile_guide/ to change.

#### What happened instead?

The links are the same as on https://app.element.io/mobile_guide/

### Operating system

_No response_

### Browser information

_No response_

### URL for webapp

_No response_

### Application version

Built from commit 71800ba2

### Homeserver

_No response_

### Will you send logs?

No