Fix deleting integrations with duplicate names (#3397)

# What this PR does

Fixes a bug when it's not possible to delete two or more integrations
having the same name at once.

## Which issue(s) this PR fixes

https://github.com/grafana/oncall-private/issues/2313

## Checklist

- [x] Unit, integration, and e2e (if applicable) tests updated
- [x] Documentation added (or `pr:no public docs` PR label added if not
required)
- [x] `CHANGELOG.md` updated (or `pr:no changelog` PR label added if not
required)

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Fixed
+
+- Fix deleting integrations with duplicate names by @vadimkerr ([#3397](https://github.com/grafana/oncall/pull/3397))
+
 ## v1.3.60 (2023-11-20)
 
 ### Fixed

engine/apps/alerts/migrations/0039_remove_alertreceivechannel_unique_integration_name.py

@@ -0,0 +1,17 @@
+# Generated by Django 4.2.7 on 2023-11-21 12:25
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('alerts', '0038_remove_alertgroup_is_restricted_db'),
+    ]
+
+    operations = [
+        migrations.RemoveConstraint(
+            model_name='alertreceivechannel',
+            name='unique integration name',
+        ),
+    ]

engine/apps/alerts/models/alert_receive_channel.py

@@ -206,14 +206,6 @@ class AlertReceiveChannel(IntegrationOptionsMixin, MaintainableObject):
     rate_limited_in_slack_at = models.DateTimeField(null=True, default=None)
     rate_limit_message_task_id = models.CharField(max_length=100, null=True, default=None)
 
-    class Meta:
-        constraints = [
-            models.UniqueConstraint(
-                fields=["organization", "verbal_name", "deleted_at"],
-                name="unique integration name",
-            )
-        ]
-
     def __str__(self):
         short_name_with_emojis = emojize(self.short_name, language="alias")
         return f"{self.pk}: {short_name_with_emojis}"

engine/apps/alerts/tests/test_alert_receiver_channel.py

@@ -220,3 +220,12 @@ def test_alertmanager_available_for_heartbeat(make_organization, make_alert_rece
     organization = make_organization()
     alert_receive_channel = make_alert_receive_channel(organization, integration=integration)
     assert alert_receive_channel.is_available_for_integration_heartbeat
+
+
+@pytest.mark.django_db
+def test_delete_duplicate_names(make_organization, make_alert_receive_channel):
+    """Check that it's possible to delete two integrations with the same name at once."""
+    organization = make_organization()
+    for _ in range(2):
+        make_alert_receive_channel(organization, verbal_name="duplicate")
+    organization.alert_receive_channels.all().delete()