Drop discounts tables

Now that we've already removed the discounts framework (and shipped all
the changes), we can remove the last remnants:

4daa502

ws/merge.py

@@ -33,13 +33,11 @@
     "ws_leaderrecommendation": ("creator_id", "participant_id"),
     "ws_lectureattendance": ("participant_id", "creator_id"),
     "ws_winterschoolsettings": ("last_updated_by_id",),
-    "ws_discount_administrators": ("participant_id",),
     "ws_distinctaccounts": ("left_id", "right_id"),
     # Each of these tables should only have one row for the given person.
     # (For example, it's possible that two participants representing the same human are on the same trip.
     # In practice, though, this should never actually be happening. Uniqueness constraints will protect us.
     "ws_tripinfo_drivers": ("participant_id",),
-    "ws_participant_discounts": ("participant_id",),
     "ws_trip_leaders": ("participant_id",),
     "ws_leadersignup": ("participant_id",),
     "ws_signup": ("participant_id",),

ws/migrations/0005_remove_participant_discounts_delete_discount.py

@@ -0,0 +1,19 @@
+# Generated by Django 4.2.16 on 2024-09-07 17:03
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("ws", "0004_index_on_bools"),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name="participant",
+            name="discounts",
+        ),
+        migrations.DeleteModel(
+            name="Discount",
+        ),
+    ]