Diag: clear machineEventSet on the begin of DCDiag ...

... not on end.
This is to keep current machineEventSet during normal IDLE process.

src/ATBAPP/DeviceControllerDiag.cpp

@@ -58,6 +58,7 @@ void DeviceControllerDiag::diagRequest()
         qCritical() << "DeviceControllerDiag::diagRequest() is already running";
         return;
     }
+    this->machineEventSet.clear();
     this->isRequestRunning = true;
     this->diagRequestTimeoutTimer->start();
 
@@ -432,7 +433,6 @@ void DeviceControllerDiag::sub_componentAssessment()
     this->flagInterruptDiag = false;
 
     this->previousMachineEventSet = machineEventSet;
-    this->machineEventSet.clear();
 }