e2e framework change to find empty throttler config (vitessio#17228)

Signed-off-by: Harshit Gangal <harshit@planetscale.com>
Signed-off-by: Renan Rangel <rrangel@slack-corp.com>

Author: harshit-gangal

go/vt/vttablet/endtoend/framework/server.go

@@ -65,11 +65,16 @@ func StartCustomServer(ctx context.Context, connParams, connAppDebugParams mysql
 		TabletType: topodatapb.TabletType_PRIMARY,
 	}
 	TopoServer = memorytopo.NewServer(ctx, "")
+	// Create the serving keyspace for throttler.
+	err := TopoServer.UpdateSrvKeyspace(ctx, "", "vttest", &topodatapb.SrvKeyspace{})
+	if err != nil {
+		return vterrors.Wrap(err, "could not create serving keyspace in topo")
+	}
 
 	srvTopoCounts := stats.NewCountersWithSingleLabel("", "Resilient srvtopo server operations", "type")
 	Server = tabletserver.NewTabletServer(ctx, vtenv.NewTestEnv(), "", cfg, TopoServer, &topodatapb.TabletAlias{}, srvTopoCounts)
 	Server.Register()
-	err := Server.StartService(Target, dbcfgs, nil /* mysqld */)
+	err = Server.StartService(Target, dbcfgs, nil /* mysqld */)
 	if err != nil {
 		return vterrors.Wrap(err, "could not start service")
 	}