tiflash may stuck by logger when log rorating.

[LittleFall]

When poco logger rotating, all the log of tiflash will be hang.

Bug Report

log rorate blocking all log beviours from other threads including GRPC

1. Minimal reproduce step (Required)

1.let log rorating occur. such as：use trace log level

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

there will be logs as soon as log rorate occur.

3. What did you see instead (Required)

there will be no log for a few seconds when log rorate occur.

4. What is your TiFlash version? (Required)

All

[LittleFall]

cc @bestwoody