closes: CORE-34
refs: https://github.com/TryGhost/Team/issues/1044
- this is a super basic fix, it adds a max nodes concept and limits the node in each sub-sitemap to 50k by default
- this will prevent the error in google console
- a better fix is in progress, but we want to at least solve the errors ASAP
- we moved the meta folder out of data a really long time ago
- we also moved the sitemap out of data/xml into a service
- this moves the tests to roughly match