pd panic when br restore data for serverless product

[Lily2025]

Bug Report

What did you do?

br restore data

What did you expect to see?

no panic

What did you see instead?

pd panic

{"container":"pd","namespace":"testbed-glh-serverless-pr9hz","pod":"tc-pd-0","log":"[log.go:87] [panic] [recover="\"invalid memory address or nil pointer dereference\""] [stack="github.com/tikv/pd/pkg/utils/logutil.LogPanic\n\t/go/src/github.com/tikv/pd/pkg/utils/logutil/log.go:87\nruntime.gopanic\n\t/usr/local/go/src/runtime/panic.go:914\nruntime.panicmem\n\t/usr/local/go/src/runtime/panic.go:261\nruntime.sigpanic\n\t/usr/local/go/src/runtime/signal_unix.go:861\ngithub.com/tikv/pd/pkg/schedule.(*Coordinator).GetPrepareChecker\n\t/go/src/github.com/tikv/pd/pkg/schedule/coordinator.go:794\ngithub.com/tikv/pd/server/cluster.(*schedulingController).IsPrepared\n\t/go/src/github.com/tikv/pd/server/cluster/scheduling_controller.go:474\ngithub.com/tikv/pd/server/cluster.(*RaftCluster).checkStores\n\t/go/src/github.com/tikv/pd/server/cluster/cluster.go:1718\ngithub.com/tikv/pd/server/cluster.(*RaftCluster).runNodeStateCheckJob\n\t/go/src/github.com/tikv/pd/server/cluster/cluster.go:693"]","level":"FATAL"}

What version of PD are you using (pd-server -V)?

./pd-server -V
Release Version: v7.1.1-serverless
Edition: Community
Git Commit Hash: 5bf0c14
Git Branch: release-7.1-keyspace
UTC Build Time: 2024-01-18 06:15:45
2024-01-19T10:01:36.029+0800

[Lily2025]

/type bug
/severity critical
/assign rleungx