Remove the "event feed starts to check locked regions" log 🔥🔥🔥

[kennytm]

Is your feature request related to a problem?

The CDC log is full of these useless entries. It makes the CDC log very large, and thus the log file very slow to open for reading, and very annoying to locate any actual problem.

$ wc -l cdc-1.log
  247586 cdc-1.log
$ rg -c 'event feed starts to check locked regions' cdc-1.log
242538
$ echo $(( 242538.0 / 247586 ))
0.97961112502322423

Describe the feature you'd like

Reduce the log level to DEBUG or just nuke it from orbit.

tiflow/cdc/kv/shared_client.go

Lines 838 to 840 in f79c7ce

	log.Info("event feed starts to check locked regions",
	zap.String("namespace", s.changefeed.Namespace),
	zap.String("changefeed", s.changefeed.ID))

Describe alternatives you've considered

No response

Teachability, Documentation, Adoption, Migration Strategy

No response

[lance6716]

Also we can use the sampling feature of zap logger

https://github.com/pingcap/tidb/blob/6773734a41e1710665a08eedd23f2d747187014d/pkg/util/logutil/log.go#L433