fix(alert): Delete IncidentTrigger as child of AlertRuleTrigger (#101460)

There can be 10s-100s of thousands of IncidentTrigger rows associated
with an AlertRuleTrigger.
In SENTRY-4A76, we see repeated failed attempts to delete an
AlertRuleTrigger with 15k IncidentTriggers, and this change will
hopefully help there.

Author: kcons

src/sentry/deletions/defaults/alert_rule_trigger.py

@@ -5,9 +5,11 @@
 class AlertRuleTriggerDeletionTask(ModelDeletionTask[AlertRuleTrigger]):
     def get_child_relations(self, instance: AlertRuleTrigger) -> list[BaseRelation]:
         from sentry.incidents.models.alert_rule import AlertRuleTriggerAction
+        from sentry.incidents.models.incident import IncidentTrigger
         from sentry.workflow_engine.models import DataConditionAlertRuleTrigger
 
         return [
             ModelRelation(AlertRuleTriggerAction, {"alert_rule_trigger_id": instance.id}),
+            ModelRelation(IncidentTrigger, {"alert_rule_trigger_id": instance.id}),
             ModelRelation(DataConditionAlertRuleTrigger, {"alert_rule_trigger_id": instance.id}),
         ]

tests/sentry/deletions/test_alert_rule_trigger.py

@@ -1,5 +1,6 @@
 from sentry.deletions.tasks.scheduled import run_scheduled_deletions
 from sentry.incidents.models.alert_rule import AlertRule, AlertRuleTrigger, AlertRuleTriggerAction
+from sentry.incidents.models.incident import IncidentTrigger, TriggerStatus
 from sentry.testutils.hybrid_cloud import HybridCloudTestMixin
 from sentry.workflow_engine.models import DataConditionAlertRuleTrigger
 from tests.sentry.workflow_engine.test_base import BaseWorkflowTest
@@ -16,6 +17,12 @@ def test_simple(self) -> None:
         DataConditionAlertRuleTrigger.objects.create(
             data_condition=data_condition, alert_rule_trigger_id=alert_rule_trigger.id
         )
+        incident = self.create_incident(alert_rule=alert_rule)
+        incident_trigger = self.create_incident_trigger(
+            incident=incident,
+            alert_rule_trigger=alert_rule_trigger,
+            status=TriggerStatus.ACTIVE.value,
+        )
 
         self.ScheduledDeletion.schedule(instance=alert_rule_trigger, days=0)
 
@@ -25,6 +32,7 @@ def test_simple(self) -> None:
         assert AlertRule.objects.filter(id=alert_rule.id).exists()
         assert not AlertRuleTrigger.objects.filter(id=alert_rule_trigger.id).exists()
         assert not AlertRuleTriggerAction.objects.filter(id=alert_rule_trigger_action.id).exists()
+        assert not IncidentTrigger.objects.filter(id=incident_trigger.id).exists()
         assert not DataConditionAlertRuleTrigger.objects.filter(
             alert_rule_trigger_id=alert_rule_trigger.id
         ).exists()