CLDC-4141: cleanup export field filtering

app/services/exports/lettings_log_export_constants.rb

@@ -161,6 +161,7 @@ module Exports::LettingsLogExportConstants
     EXPORT_FIELDS << "age#{index}"
     EXPORT_FIELDS << "ecstat#{index}"
     EXPORT_FIELDS << "sex#{index}"
+    EXPORT_FIELDS << "sexrab#{index}"
   end
   (2..8).each do |index|
     EXPORT_FIELDS << "relat#{index}"

app/services/exports/lettings_log_export_service.rb

@@ -172,7 +172,6 @@ module Exports
       details_known_prefix = "details_known_"
       included_fields = Set[]
       included_fields.merge(EXPORT_FIELDS)
-      included_fields.merge(POST_2026_EXPORT_FIELDS)
 
       if lettings_log.form.start_year_2024_or_later?
         included_fields.subtract(PRE_2024_EXPORT_FIELDS)