"You are about to view pages over a secure connection" in IE 10

I'm trying to turn off the pop up message "You are about to view pages over a secure connection" via GPO but can't find the option.  I know there is a reg key ([HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Security] "DisableSecuritySettingCheck"=dword:00000001) but trying to find it in Group Policy seems impossible. 

Can anyone advise where it is?

Thanks!