[FIX] sale_coupon: do not deduce reward quantity on current_order

Before this commit:
1. We were checking if the rewards were in the SO even if it was 'next_order'
   program.
2. We were deducing the rewards quantity for 'next_order' program when checking
   if we had enough products to meet the program requirements.

Now:
1. We don't verify if the reward is on the SO if the program is 'next_order'
2. We don't deduce reward quantity when checking if enough products to meet the
   program requirements if the program is 'next_order'

opw-1907211
Closes #3062

tests/test_program_numbers.py

@@ -489,3 +489,31 @@ class TestSaleCouponProgramNumbers(TestSaleCouponCommon):
         fixed_amount_program.write({'active': False})  # Check archived product will remove discount lines on recompute
         order.recompute_coupon_lines()
         self.assertEqual(len(order.order_line.ids), 1, "Archiving the program should remove the program reward line")
+
+    def test_program_next_order(self):
+        order = self.empty_order
+        self.env['sale.coupon.program'].create({
+            'name': 'Free Keyboard if at least 1 article',
+            'promo_code_usage': 'no_code_needed',
+            'promo_applicability': 'on_next_order',
+            'program_type': 'promotion_program',
+            'reward_type': 'product',
+            'reward_product_id': self.wirelessKeyboard.id,
+            'rule_min_quantity': 2,
+        })
+        sol1 = self.env['sale.order.line'].create({
+            'product_id': self.iPadMini.id,
+            'name': 'iPad Mini',
+            'product_uom_qty': 1.0,
+            'order_id': order.id,
+        })
+        order.recompute_coupon_lines()
+        self.assertEqual(len(order.order_line.ids), 1, "Nothing should be added to the cart")
+        self.assertEqual(len(order.generated_coupon_ids), 0, "No coupon should have been generated yet")
+
+        sol1.product_uom_qty = 2
+        order.recompute_coupon_lines()
+        generated_coupon = order.generated_coupon_ids
+        self.assertEqual(len(order.order_line.ids), 1, "Nothing should be added to the cart (2)")
+        self.assertEqual(len(generated_coupon), 1, "A coupon should have been generated")
+        self.assertEqual(generated_coupon.state, 'reserved', "The coupon should be reserved")