Add missing migration for Partners & AssignedReviewers (#4804)

Related to #4790. I missed an edge case where an `AssignedReviewer` was
also a Partner, in which the migrations would fail as the `type`
attribute is protected in the model. This moves all types of partner to
reviewer.

---------

Co-authored-by: Fredrik Jonsson <frjo@xdeb.org>

Author: wes-otf

hypha/apply/users/migrations/0028_remove_partner_group.py

@@ -1,14 +1,34 @@
 # Generated by Django 5.2.12 on 2026-03-26 19:48
 
 from django.db import migrations
-from django.contrib.auth.models import Group
 
 
-def migrate_partners_to_coapplicants(apps, schema_editor):
+# An edge case that won't apply to most systems
+def assigned_review_migrate_from_partners(apps, schema_editor):
     PARTNER_GROUP_NAME = "Partner"
+    REVIEWER_GROUP_NAME = "Reviewer"
 
-    if Group.objects.filter(name=PARTNER_GROUP_NAME).exists():
-        Group.objects.get(name=PARTNER_GROUP_NAME).delete()
+    Group = apps.get_model("auth", "Group")
+    AssignedReviewers = apps.get_model("funds", "AssignedReviewers")
+
+    try:
+        reviewer_id = Group.objects.get(name=REVIEWER_GROUP_NAME).id
+    except Group.DoesNotExist:
+        return
+
+    if id_qs := Group.objects.filter(name=PARTNER_GROUP_NAME).values_list(
+        "id", flat=True
+    ):
+        AssignedReviewers.objects.filter(type_id=id_qs.first()).update(
+            type_id=reviewer_id
+        )
+
+
+def delete_partner_group(apps, schema_editor):
+    PARTNER_GROUP_NAME = "Partner"
+
+    Group = apps.get_model("auth", "Group")
+    Group.objects.filter(name=PARTNER_GROUP_NAME).delete()
 
 
 class Migration(migrations.Migration):
@@ -17,4 +37,9 @@ class Migration(migrations.Migration):
         ("funds", "0133_remove_applicationsubmission_partners"),
     ]
 
-    operations = [migrations.RunPython(migrate_partners_to_coapplicants)]
+    operations = [
+        migrations.RunPython(
+            assigned_review_migrate_from_partners, migrations.RunPython.noop
+        ),
+        migrations.RunPython(delete_partner_group, migrations.RunPython.noop),
+    ]