models: Enforce an ordering to on audit logs to solve a flaky test.

Multiple events may be created with the same timestamp; we add a
default ordering by "id" such that these have a consistent ordering in
tests (to solve for flaky tests), as well as in the internal API.

zerver/models/realm_audit_logs.py

@@ -226,6 +226,7 @@ class RealmAuditLog(AbstractRealmAuditLog):
     event_last_message_id = models.IntegerField(null=True)
 
     class Meta:
+        ordering = ["id"]
         indexes = [
             models.Index(
                 name="zerver_realmauditlog_realm__event_type__event_time",