Discount code quantity calculation logic is completely wrong

[iamareebjamal]

open-event-server/app/api/helpers/ticketing.py

Lines 35 to 41 in 1aebc2f

	old_holders = get_count(
	TicketHolder.query.filter(
	TicketHolder.ticket_id.in_(ticket_ids) # pytype: disable=attribute-error
	)
	.join(Order)
	.filter(Order.status.in_(['completed', 'placed']))
	)

This just calculates all the bought tickets, and not the tickets bought with discount code. God knows how it was supposed to work.

Secondly, discount code should be redesigned as it is confusing, it is applicable to individual ticket instead of entire order, but is saved with the order instead. This needs to be discussed and decided later on as it is impossible to check which tickets the discount code was applied to in the order