Set the default value for the search engine visibility for non-system pages.
Set the default value for the search engine visibility for non-system pages.

Closes #2482

This sets the default value, the `page.xml` runs shortly afterwards to
set the actual values, making this merely a safe-guard for
backwards-compatibility.

SoftCreatR/WCF,WoltLab/WCF,SoftCreatR/WCF,Morik/WCF,Cyperghost/WCF,Cyperghost/WCF,Morik/WCF,Cyperghost/WCF,Morik/WCF,Morik/WCF,WoltLab/WCF,MenesesEvandro/WCF,SoftCreatR/WCF,WoltLab/WCF,Cyperghost/WCF,Cyperghost/WCF,MenesesEvandro/WCF,WoltLab/WCF,SoftCreatR/WCF