fix: modified code to use flush() when internal queue is not loaded

https://telecominfraproject.atlassian.net/browse/WIFI-13857

NOTE: This is port of Telecominfraproject/wlan-cloud-ucentralgw#362

Signed-off-by: Ivan Chvets <ivan.chvets@kinarasystems.com>

Author: i-chvets

src/framework/KafkaManager.cpp

@@ -107,7 +107,16 @@ namespace OpenWifi {
 					NewMessage.partition(0);
 					NewMessage.payload(Msg->Payload());
 					Producer.produce(NewMessage);
-					Producer.poll((std::chrono::milliseconds) 0);
+					if (Queue_.size() < 100) {
+						// use flush when internal queue is lightly loaded, i.e. flush after each
+						// message
+						Producer.flush();
+					}
+					else {
+						// use poll when internal queue is loaded to allow messages to be sent in
+						// batches
+						Producer.poll((std::chrono::milliseconds) 0);
+					}
 				}
 			} catch (const cppkafka::HandleException &E) {
 				poco_warning(Logger_,