Remove `camptix_form_attendee_info_before` from payment-stripe constr…

[vedanshujain]

…uctor class. It looks likes this is only needed in when we actually render the payment page, so do_action in form_attendee_info method in camptix.php should be good enough.

[coreymckrill]

We still need to hook into the do_action call, so that the Stripe scripts get enqueued, etc. So we can't remove that line entirely, but there is a mistake in it. It should be add_action instead of add_filter.