Those files are not included by default in /usr/share/openstack-tripleo-heat-templates/network/config/*** , you will find Jinja files instead (same for network-environment files reviewed in section 9.2). That should be explained in the DOCs https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/13/html/advanced_overcloud_customization/sect-isolating_networks#annotations:0c83a9fc-9b66-47cc-a000-59f66d7cddf9
This content is very out of date. Am currently rewriting this whole section.
This content has been significantly revised including steps for Jinja2 templates. See the following revised/new sections: https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/13/html/advanced_overcloud_customization/basic-network-isolation https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/13/html/advanced_overcloud_customization/custom-composable-networks https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/13/html/advanced_overcloud_customization/custom-network-interface-templates