Statistics is still a dummy implementation

**Describe the bug**
PublicStatistics.vue is still a dummy implementation. The data source is a hardcoded constant:

```
const data = [
  {
    zip: '12345',
    active: '320',
    suspicion: '742',
    recovered: '135',
    deaths: '12',
  },
...
```

**Expected behavior**
The statistics feature should either be implemented or removed.