Make ioi16 related files cleaner

judge/migrations/0144_auto_20230103_0523.py

@@ -0,0 +1,28 @@
+# Generated by Django 3.2.16 on 2023-01-02 22:23
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("judge", "0143_auto_20221229_0153"),
+    ]
+
+    operations = [
+        migrations.RemoveField(
+            model_name="contestproblem",
+            name="frozen_subtasks",
+        ),
+        migrations.AddField(
+            model_name="contestproblem",
+            name="hidden_subtasks",
+            field=models.CharField(
+                blank=True,
+                help_text="Separated by commas, e.g: 2, 3",
+                max_length=20,
+                null=True,
+                verbose_name="hidden subtasks",
+            ),
+        ),
+    ]