DEV: skip topic deletion staff log when user skip new user tips.

Previously, every time when a user skipped the "new user tips" it will add a staff action log since the discobot's welcome post is destroyed.

plugins/discourse-narrative-bot/spec/user_spec.rb

@@ -119,7 +119,10 @@ describe User do
       it 'should delete the existing PM' do
         user.user_option.skip_new_user_tips = true
 
-        expect { user.user_option.save! }.to change { Topic.count }.by(-1)
+        expect {
+          user.user_option.save!
+        }.to change { Topic.count }.by(-1)
+          .and change { UserHistory.count }.by(0)
       end
     end