chore: reduce Kafka clients lib log verbosity

Signed-off-by: Benjamin Voiturier <benjamin.voiturier@iohk.io>

cloud-agent/service/server/src/main/resources/logback.xml

@@ -13,6 +13,9 @@
   <logger name="io.getquill" level="WARN">
     <appender-ref ref="STDOUT" />
   </logger>
+  <logger name="org.apache.kafka.clients" level="WARN">
+    <appender-ref ref="STDOUT" />
+  </logger>
   <root level="info">
     <appender-ref ref="STDOUT"/>
   </root>