remove landuse=farm preset

https://github.com/openstreetmap/id-tagging-schema/blob/e73d5194b9d0274d8bb6b89586e256b4c57660b7/data/presets/landuse/_farm.json it basically went extinct, see https://taginfo.openstreetmap.org/tags/landuse=farm `landuse=farm` was deprecated because it was unclear is it landuse=farmland or farmyard while it is misrepresented in presets as landuse=farmland I think it can be safely removed nowadays