fix(data-planes) access log missing new line

With the TrafficLog policy, using a custom format with the `type: file` makes the
data-planes concatenate all the Access Logs until a new Log is
generated. This bug is not observed when omiting the format.
This is fixed by addind a new line after each Access Log.
For more informations see #820

app/kuma-dp/pkg/dataplane/accesslogs/sender.go

@@ -30,7 +30,7 @@ func (s *sender) Connect() error {
 }
 
 func (s *sender) Send(record string) error {
-	_, err := s.conn.Write(append([]byte(record), byte('\n')))
+	_, err := s.conn.Write([]byte(record))
 	return errors.Wrapf(err, "failed to send a log entry to a TCP logging backend: %s", s.address)
 }
 

pkg/xds/envoy/listeners/access_log_configurer.go

@@ -46,7 +46,8 @@ func convertLoggingBackend(mesh string, trafficDirection TrafficDirection, sourc
 	if backend.Format != "" {
 		formatString = backend.Format
 	}
-	format, err := accesslog.ParseFormat(formatString)
+
+	format, err := accesslog.ParseFormat(formatString + "\n")
 	if err != nil {
 		return nil, errors.Wrapf(err, "invalid access log format string: %s", formatString)
 	}