fix: remove duplicate wrong error log in socket/fetch handler and dead code in reliablePing

Former-commit-id: d57b7ccb53

main.go

@@ -1482,10 +1482,6 @@ persistent_keepalive_interval=5`, util.FixKey(privateKey.String()), util.FixKey(
 		err = client.SendMessage("newt/socket/containers", map[string]interface{}{
 			"containers": containers,
 		})
-		if err != nil {
-			logger.Error("Failed to send registration message: %v", err)
-		}
-
 		if err != nil {
 			logger.Error("Failed to send Docker container list: %v", err)
 		} else {