Discourse.SiteSettings
* Remove unused Discourse.SiteSettings * Remove `Discourse.SiteSettings` from many tests * REFACTOR: `lib:formatter` was using a lot of leaky state * Remove more `Discourse.SiteSettings` from tests * More SiteSettings removed from tests
Also fixes missed imports in core.
This reverts commit 2abe85b8344de1102c1589a9ac9421a8b296f2b5.