LPS-47659  Reordering private pages from 'Site Pages' section does not work

The issue was caused by LPS-32515.

For public layout, we may set View Permission for Guest Role. However, for private layout, Guest Role can't access it. 

So we should add "&& layout.isPublicLayout()" to filter private layout because Guest role can't have "View Permission" for private layout.

Thanks,
Hai