tags および tag_names にて論理削除を物理削除に変更 (#416) (#418)

Reviewed-on: #418
Co-authored-by: miteruzo <miteruzo@naver.com>

backend/spec/tasks/nico_sync_spec.rb

@@ -8,8 +8,7 @@ RSpec.describe 'nico:sync' do
   end
 
   def create_tag!(name, category:)
-    tn = TagName.find_undiscard_or_create_by!(name: name.to_s.strip)
-    Tag.find_undiscard_or_create_by!(tag_name_id: tn.id) { |t| t.category = category }
+    Tag.find_or_create_by_tag_name!(name, category:)
   end
 
   def link_nico_to_tag!(nico_tag, tag)