mqtt heartbeat, no need to check if connected

src/core/system.cpp

@@ -731,11 +731,6 @@ void System::heartbeat_json(JsonObject output) {
 
 // send periodic MQTT message with system information
 void System::send_heartbeat() {
-    // don't send heartbeat if WiFi or MQTT is not connected
-    if (!Mqtt::connected()) {
-        return;
-    }
-
     refreshHeapMem(); // refresh free heap and max alloc heap
 
     JsonDocument doc;