fix(sink): should support delimiter format

Signed-off-by: Jiyong Huang <huangjy@emqx.io>

internal/topo/node/sink_node.go

@@ -282,7 +282,7 @@ func (m *SinkNode) parseConf(logger api.Logger) (*SinkConf, error) {
 	m.concurrency = sconf.Concurrency
 	if sconf.Format == "" {
 		sconf.Format = "json"
-	} else if sconf.Format != message.FormatJson && sconf.Format != message.FormatProtobuf && sconf.Format != message.FormatBinary && sconf.Format != message.FormatCustom {
+	} else if sconf.Format != message.FormatJson && sconf.Format != message.FormatProtobuf && sconf.Format != message.FormatBinary && sconf.Format != message.FormatCustom && sconf.Format != message.FormatDelimited {
 		logger.Warnf("invalid type for format property, should be json protobuf or binary but found %s", sconf.Format)
 		sconf.Format = "json"
 	}