Migrate logging to structured logging

[paullaffitte]

With structured logging, log messages are no longer formatted, leaving argument marshalling up to the logging client implementation. This allows messages to be a static description of event.

All string formatting (%d, %v, %w, %s) should be removed and log message string simplified. Describing arguments in log messages is no longer needed and should be removed leaving only a description of what happened.

https://github.com/kubernetes/community/blob/master/contributors/devel/sig-instrumentation/migration-to-structured-logging.md
https://kubernetes.io/blog/2020/09/04/kubernetes-1-19-introducing-structured-logs/