Change a chatty log message from Info to Debug by request.  The message (#6170)

just logs that it is polling a traffic monitor

(cherry picked from commit a971b6c50b6a429ddbbbdfd2ca8ff1107b659eb8)
diff --git a/cache-config/tm-health-client/tmagent/tmagent.go b/cache-config/tm-health-client/tmagent/tmagent.go
index 85329d8..3006d27 100644
--- a/cache-config/tm-health-client/tmagent/tmagent.go
+++ b/cache-config/tm-health-client/tmagent/tmagent.go
@@ -405,7 +405,7 @@
 		return "", errors.New("there are no available traffic monitors")
 	}
 
-	log.Infof("polling: %s\n", tmHostname)
+	log.Debugf("polling: %s\n", tmHostname)
 
 	return tmHostname, nil
 }