don't print unnecessary log message (#3255)
don't print unnecessary log message (#3255)

When a probe keeps unavailable for a while, the target file
is already removed, and os.Remove returns a not-exist error.
We don't want to flood the log with not-exist errors.
geeknoid/istio,geeknoid/istio,frankbu/istio,frankbu/istio,smawson/istio,frankbu/istio,istio/istio,geeknoid/istio,istio/istio,smawson/istio,smawson/istio,smawson/istio,geeknoid/istio,geeknoid/istio,frankbu/istio,istio/istio,istio/istio,frankbu/istio,smawson/istio,frankbu/istio,geeknoid/istio,istio/istio,smawson/istio