add channel__team to internal api serializer select_related (#1805)

Locally I reproduced a slow `GET /api/internal/v1/alertgroups` query
(took 9s - 10s). After adding this line to the alert group serializer
for the internal api it:
- cut the response time in half
- cut the number of executed SQL queries from 52 to 30

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Helm chart: Fix helm hook for db migration job
+- Performance improvements to `GET /api/internal/v1/alertgroups` endpoint by @joeyorlando and @iskhakov ([#1805](https://github.com/grafana/oncall/pull/1805))
 
 ## v1.2.14 (2023-04-19)
 

engine/apps/api/serializers/alert_group.py

@@ -99,6 +99,7 @@ class AlertGroupListSerializer(EagerLoadingMixin, AlertGroupFieldsCacheSerialize
 
     SELECT_RELATED = [
         "channel__organization",
+        "channel__team",
         "root_alert_group",
         "resolved_by_user",
         "acknowledged_by_user",