Automatic merge from submit-queue (batch tested with PRs 54460, 55258, 54858, 55506, 55510). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Fix CRI fluentd config.

This should fix the cri-containerd stackdriver test failure:
```
Cluster level logging implemented by Stackdriver should ingest logs
```

I copied the pattern from a comment previously. However, it doesn't actually work properly. `\b` only matches word boundary, and seems to match the boundary of previous word in our case.

That's why we get the log with a leading space:
```
Nov 10 18:39:11.661: INFO: Unexpected error occurred: log entry ingested incorrectly, got --> <--I0101 00:00:00.000000       1 main.go:1] Text, want Text
```

@kubernetes/sig-node-bugs @kubernetes/sig-instrumentation-bugs 
Signed-off-by: Lantao Liu <lantaol@google.com>

```release-note
none
```