Fix SelectedAdministrativeCriteria.certification_period

The API particulier computed the dateFin with dateDebut + 3 months.
That’s very misleading, as a person who has been a beneficiary since
2009-06-01 would have:
```json
{
    "statut": "beneficiaire",
    "dateDebut": "2009-06-01",
    "dateFin": "2009-09-01",
}
```

However, the `statut` means the person is beneficiary **today**.

The API recently evolved to always set `dateFin` to `null` to avoid
suggesting the end date is known and in the past.

Fix about 11,000 incorrect records, by using `certified_at`: if the API
response for `statut` was "beneficiaire", that person was beneficiary on
the day the API was queried.

The example from above comes from the production environment and is an
example of bad data.

itou/eligibility/migrations/0009_fix_selectedadministrativecriteria_certification_period.py

@@ -0,0 +1,29 @@
+import datetime
+
+from django.db import migrations
+from django.utils import timezone
+
+from itou.utils.types import InclusiveDateRange
+
+
+def set_certification_period_end_date(apps, editor):
+    SelectedAdministrativeCriteria = apps.get_model("eligibility", "SelectedAdministrativeCriteria")
+    crits = []
+    for crit in SelectedAdministrativeCriteria.objects.exclude(certification_period=None):
+        crit.certification_period = InclusiveDateRange(
+            crit.certification_period.lower,
+            timezone.localdate(crit.certified_at) + datetime.timedelta(days=92),
+        )
+        crits.append(crit)
+    updated_objs = SelectedAdministrativeCriteria.objects.bulk_update(crits, fields=["certification_period"])
+    print(f"Updated {updated_objs} selected administrative criteria.")
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("eligibility", "0008_alter_eligibilitydiagnosis_expires_at_and_more"),
+    ]
+
+    operations = [
+        migrations.RunPython(set_certification_period_end_date, elidable=True),
+    ]