The integration test ddl_for_split_tables_random_schedule causes CDC to panic on next gen mode #2561
Description
[2025/10/09 17:45:34.693 +08:00] [FATAL] [span_op.go:74] ["IsCompleteSpan GetKeyspaceTableRange failed"] [keyspaceID=0] [stack="github.com/pingcap/ticdc/pkg/common.IsCompleteSpan\n\tgithub.com/pingcap/ticdc/pkg/common/span_op.go:74\ngithub.com/pingcap/ticdc/downstreamadapter/dispatcher.NewBasicDispatcher\n\tgithub.com/pingcap/ticdc/downstreamadapter/dispatcher/basic_dispatcher.go:190\ngithub.com/pingcap/ticdc/downstreamadapter/dispatcher.NewEventDispatcher\n\tgithub.com/pingcap/ticdc/downstreamadapter/dispatcher/event_dispatcher.go:68\ngithub.com/pingcap/ticdc/downstreamadapter/dispatchermanager.(*DispatcherManager).mergeEventDispatcher\n\tgithub.com/pingcap/ticdc/downstreamadapter/dispatchermanager/dispatcher_manager.go:767\ngithub.com/pingcap/ticdc/downstreamadapter/dispatchermanager.(*DispatcherManager).MergeDispatcher\n\tgithub.com/pingcap/ticdc/downstreamadapter/dispatchermanager/dispatcher_manager.go:745\ngithub.com/pingcap/ticdc/downstreamadapter/dispatchermanager.(*MergeDispatcherRequestHandler).Handle\n\tgithub.com/pingcap/ticdc/downstreamadapter/dispatchermanager/helper.go:508\ngithub.com/pingcap/ticdc/utils/dynstream.(*stream[...]).handleLoop\n\tgithub.com/pingcap/ticdc/utils/dynstream/stream.go:284"]