Force index only on list & stats (#4734)

Following up on #4731

engine/apps/api/views/alert_group.py

@@ -332,7 +332,7 @@ def get_queryset(self, ignore_filtering_by_available_teams=False):
         alert_receive_channels_ids = list(alert_receive_channels_qs.values_list("id", flat=True))
         queryset = AlertGroup.objects.filter(channel__in=alert_receive_channels_ids)
 
-        if settings.ALERT_GROUPS_DISABLE_PREFER_ORDERING_INDEX:
+        if self.action in ("list", "stats") and settings.ALERT_GROUPS_DISABLE_PREFER_ORDERING_INDEX:
             # workaround related to MySQL "ORDER BY LIMIT Query Optimizer Bug"
             # read more: https://hackmysql.com/infamous-order-by-limit-query-optimizer-bug/
             from django_mysql.models import add_QuerySetMixin