Remove data_migration:set_disease_types

This has been run in production so it can now be safely removed.

Jira-Issue: MAV-2858

Author: thomasleese

lib/tasks/data_migration.rake

@@ -5,17 +5,4 @@ namespace :data_migration do
   task delete_clinic_session_notifications: :environment do
     SessionNotification.where(type: [1, 2]).delete_all
   end
-
-  desc "Set disease types on vaccination records."
-  task set_disease_types: :environment do
-    VaccinationRecord
-      .includes(:vaccine)
-      .where(disease_types: nil)
-      .find_each do |vaccination_record|
-        disease_types =
-          vaccination_record.vaccine&.disease_types ||
-            vaccination_record.programme.disease_types
-        vaccination_record.update_columns(disease_types:)
-      end
-  end
 end