Currently identical builder entities are maintained in `template_unit_infantry.xml`, `template_unit_support_female_citizen.xml`, and `template_unit_support_slave.xml`.
This patch removes those from the latter two and inserts it into `template_unit_support.xml` and inserts `<Builder disable=""/>` in its other three children, effectively saving lines and making things easier to maintain.
In principle it could be moved to `template_unit.xml` instead, allowing the build list to be removed from `template_unit_infantry.xml` as well, but that would require `<Builder disable=""/>` in more files.