Avoid crashing live loader in case the network is interrupted. (#5268)

Live loader currently runs `x.Fatalf` the moment it has a connection interrupt. Instead, it should just retry indefinitely.

Also, remove a `%+v` error print for aborting transactions, which causes the entire error stack trace to be printed, which makes it look like a crash.

dgraph/cmd/live/batch.go

@@ -114,7 +114,12 @@ func handleError(err error, isRetry bool) {
 	s := status.Convert(err)
 	switch {
 	case s.Code() == codes.Internal, s.Code() == codes.Unavailable:
-		x.Fatalf(s.Message())
+		// Let us not crash live loader due to this. Instead, we should infinitely retry to
+		// reconnect and retry the request.
+		dur := time.Duration(1+rand.Intn(60)) * time.Second
+		fmt.Printf("Connection has been possibly interrupted. Got error: %v."+
+			" Will retry after %s.\n", err, dur.Round(time.Second))
+		time.Sleep(dur)
 	case strings.Contains(s.Message(), "x509"):
 		x.Fatalf(s.Message())
 	case s.Code() == codes.Aborted:

worker/draft.go

@@ -1289,7 +1289,7 @@ func (n *node) abortOldTransactions() {
 	glog.Infof("Found %d old transactions. Acting to abort them.\n", len(starts))
 	req := &pb.TxnTimestamps{Ts: starts}
 	err := n.blockingAbort(req)
-	glog.Infof("Done abortOldTransactions for %d txns. Error: %+v\n", len(req.Ts), err)
+	glog.Infof("Done abortOldTransactions for %d txns. Error: %v\n", len(req.Ts), err)
 }
 
 // calculateSnapshot would calculate a snapshot index, considering these factors: