changefeed checkpoint ts stuck with redo enabled

[lidezhu]

What did you do?

1. create 1000 sysbench tables;
2. write some data;
3. create changefeed with redo enabled;

[consistent]
level = "eventual"
storage = "file:///root/test/redo"

What did you expect to see?

changefeed checkpoint ts advance normally.

What did you see instead?

changefeed checkpoint ts stuck

Versions of the cluster

Upstream TiDB cluster version (execute SELECT tidb_version(); in a MySQL client):

(paste TiDB cluster version here)

Upstream TiKV version (execute tikv-server --version):

(paste TiKV version here)

TiCDC version (execute cdc version):

(paste TiCDC version here)