Log flooding issue in ticdc check

[yiwen92]

What did you do?

upgrade from 6.0.0 to 6.0.1, CDC running on 6.1.1, logs are quickly filled with tons of the entries similar to this one:
[2022/09/26 06:47:12.746 +00:00] [INFO] [mounter.go:265] ["column value is not found"] [table=xx] [column=xx]
[2022/09/26 06:47:12.746 +00:00] [INFO] [mounter.go:265] ["column value is not found"] [table=xx] [column=xx]
[2022/09/26 06:47:12.746 +00:00] [INFO] [mounter.go:265] ["column value is not found"] [table=xx] [column=xx]
...
it seems it reacts this way on null as column value.
Logs grow very fast (many Gb per day) on CDC nodes so I don't think it's very normal.
We don't see this issue on 6.1.0 clusters though.

What did you expect to see?

No response

What did you see instead?

Logs grow very fast (many Gb per day) on CDC nodes so I don't think it's very normal.

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):

(v6.1.1)

[yiwen92]

This was introduced by https://github.com/pingcap/tiflow/pull/6416/files. Will change the log to debug level. @hi-rustin Could you please make sure it can be fixed in v6.1.2?