PiTR task cannot get checkpoint ts

[AkiraXie]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

1. start a PiTR task

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

1. checkpoint ts can be advanced
2. br log status can get normal result

3. What did you see instead (Required)

1. checkpoint ts was not advanced
   
2. br log status got abnormal result
   

4. What is your TiDB version? (Required)

• br:

/ # /br --version
Release Version: v6.2.0-alpha
Git Commit Hash: cdcbfc838ab3d4768d5761181ca9f3ee361811ce
Git Branch: heads/refs/tags/v6.2.0-alpha
Go Version: go1.18.5
UTC Build Time: 2022-09-08 11:01:32
Race Enabled: false

• tikv:

/ # /tikv-server --version
TiKV
Release Version:   6.2.0-alpha
Edition:           Community
Git Commit Hash:   8c93b91fea7396b9261551297d1bfa037c82e605
Git Commit Branch: heads/refs/tags/v6.2.0-alpha
UTC Build Time:    2022-09-13 11:02:56
Rust Version:      rustc 1.64.0-nightly (0f4bcadb4 2022-07-30)
Enable Features:   pprof-fp jemalloc mem-profiling portable sse test-engine-kv-rocksdb test-engine-raft-raft-engine cloud-aws cloud-gcp cloud-azure
Profile:           dist_release

[AkiraXie]

/component br

[AkiraXie]

/severity critical

[AkiraXie]

/label affects-6.2