LPS-43197 Missing privateLayout parameter caused "Not Found" error on private pages

The issue reported on the LPS ticket not only happened on site templates but also for any private pages. 

In the current PortalImpl.getLayoutActualURL() it uses the key/value pairs in variables to replace the value in the url. If we do not set the corresponding privateLayout parameter it will set null in the url which would cause:
1. The private page(Link to page type) redirect to the public page
2. "Not Found" error in Site template page as site page do not have public page(Actually reported in the LPS ticket).