remote-billing: Add index to RemoteRealmAuditLog for billing events.

When profiling the database queries for the remote support view,
getting the user counts for remote realms was identifed as an
expensive query. Adds an index on RemoteRealmAuditLog to improve
this relatively common query for remote billing information.

zilencer/migrations/0059_remoterealmauditlog_add_synced_billing_event_type_index.py

@@ -0,0 +1,21 @@
+# Generated by Django 4.2.9 on 2024-02-20 12:04
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("zilencer", "0058_remoteinstallationcount_add_mobile_pushes_forwarded_index"),
+    ]
+
+    operations = [
+        migrations.AddIndex(
+            model_name="remoterealmauditlog",
+            index=models.Index(
+                condition=models.Q(("event_type__in", [101, 102, 103, 104, 105, 201, 202, 229])),
+                fields=["remote_realm_id", "id"],
+                name="zilencer_remoterealmauditlog_synced_billing_events",
+            ),
+        ),
+    ]

zilencer/models.py

@@ -333,6 +333,11 @@ class RemoteRealmAuditLog(AbstractRealmAuditLog):
                 condition=Q(remote_realm__isnull=True),
                 name="zilencer_remoterealmauditlog_server",
             ),
+            models.Index(
+                fields=["remote_realm_id", "id"],
+                condition=Q(event_type__in=AbstractRealmAuditLog.SYNCED_BILLING_EVENTS),
+                name="zilencer_remoterealmauditlog_synced_billing_events",
+            ),
         ]