Removed sysadmin group from sudoers template.

Sysadmin group does not exist on all systems. Also, since the group is assumed in the template it could be granted passwordless sudo inadvertently.

For example, a role that looks like:

```javascript
{
  "authorization": {
    "sudo": {
      "groups": ["sudo"],
      "passwordless": true
    }
  }
}
```

Would grant passwordless sudo to both the sudo group and the sysadmin group.