[Dynamic Regions] in restore point , br oomkilled

[AkiraXie]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

1. br 4c16g
2. br restore point to partitioned-raft-kv cluster

2. What did you expect to see? (Required)

3. What did you see instead (Required)

1. br oomed
   [Sat Jul 22 01:07:21 2023] Memory cgroup out of memory: Killed process 2748779 (br-fixed-3) total-vm:18009712kB, anon-rss:16348072kB, file-rss:1148kB, shmem-rss:0kB, UID:0 pgtables:32468kB oom_score_adj:-997

4. What is your TiDB version? (Required)

master

[AkiraXie]

/severity major
/component br