treewide: forbid use of selected site variables in domain specific or site configs

package/gluon-authorized-keys/check_site.lua

package/gluon-autoupdater/check_site.lua

package/gluon-client-bridge/check_site.lua

package/gluon-config-mode-contact-info/check_site.lua

package/gluon-config-mode-geo-location/check_site.lua

package/gluon-core/check_site.lua

package/gluon-ebtables-source-filter/check_site.lua

package/gluon-mesh-vpn-core/check_site.lua

package/gluon-mesh-vpn-fastd/check_site.lua

package/gluon-node-info/check_site.lua

package/gluon-setup-mode/check_site.lua

package/gluon-web-admin/check_site.lua

package/gluon-web-mesh-vpn-fastd/check_site.lua

package/gluon-web-node-role/check_site.lua