Set discount correctly in case of autodiscount

Steps to reproduce -

1. Create a discount code for one event (say test event) with Contact type Individual in Automatic discount panel (so that this applies to all individuals registering to this event).

2. Create another discount code for all events with any discount amount.

3. Navigate to test event page - Notice that discount 1 has applied automatically.

4. Complete the registration process.

Open cividiscount_track table and check that item id recorded for the participant is the id of discount created at step 2. It should contain the value of discount 1.