Panic for hot span when enable split

[hongyunyan]

run bank2 workload and enable split tables. Then we may meet

[2025/03/12 12:20:10.855 +00:00] [PANIC] [checker.go:165] ["remove hot span since it is outdated"] [changefeed=test-syncpoint] [span=391181646360979309112573740532198237863] [stack="github.com/pingcap/ticdc/maintainer/replica.(*hotSpanChecker).Check\n\tgithub.com/pingcap/ticdc/maintainer/replica/checker.go:165\ngithub.com/pingcap/ticdc/maintainer/replica.(*ReplicationDB).CheckByGroup\n\tgithub.com/pingcap/ticdc/maintainer/replica/replication_db.go:402\ngithub.com/pingcap/ticdc/maintainer.(*splitScheduler).Execute\n\tgithub.com/pingcap/ticdc/maintainer/scheduler.go:126\ngithub.com/pingcap/ticdc/pkg/scheduler.(*Controller).Start.func1\n\tgithub.com/pingcap/ticdc/pkg/scheduler/scheduler.go:70\ngithub.com/pingcap/ticdc/utils/threadpool.(*funcTaskImpl).Execute\n\tgithub.com/pingcap/ticdc/utils/threadpool/task.go:79\ngithub.com/pingcap/ticdc/utils/threadpool.(*threadPoolImpl).executeTasks\n\tgithub.com/pingcap/ticdc/utils/threadpool/thread_pool.go:81"]