[SYS] Remove handleJsonQueue wrapper and use std::string (#2038)

Co-authored-by: Florian <1technophile@users.noreply.github.com>

main/ZgatewayLORA.ino

@@ -473,11 +473,11 @@ void LORAtoMQTT() {
       LORAdataBuffer["origin"] = subjectLORAtoMQTT;
     }
 
-    handleJsonEnqueue(LORAdata);
+    enqueueJsonObject(LORAdata);
     if (repeatLORAwMQTT) {
       Log.trace(F("Pub LORA for rpt" CR));
       LORAdata["origin"] = subjectMQTTtoLORA;
-      handleJsonEnqueue(LORAdata);
+      enqueueJsonObject(LORAdata);
     }
   }
 }