FirmwareUpgradeController: remove unuse variables & use https for firmware.ardupilot.org

src/VehicleSetup/FirmwareUpgradeController.cc

@@ -109,8 +109,6 @@ FirmwareUpgradeController::FirmwareUpgradeController(void)
     : _singleFirmwareURL                (qgcApp()->toolbox()->corePlugin()->options()->firmwareUpgradeSingleURL())
     , _singleFirmwareMode               (!_singleFirmwareURL.isEmpty())
     , _downloadingFirmwareList          (false)
-    , _downloadManager                  (nullptr)
-    , _downloadNetworkReply             (nullptr)
     , _statusLog                        (nullptr)
     , _selectedFirmwareBuildType        (StableFirmware)
     , _image                            (nullptr)
@@ -688,7 +686,7 @@ void FirmwareUpgradeController::_downloadArduPilotManifest(void)
 
     QGCFileDownload* downloader = new QGCFileDownload(this);
     connect(downloader, &QGCFileDownload::downloadComplete, this, &FirmwareUpgradeController::_ardupilotManifestDownloadComplete);
-    downloader->download(QStringLiteral("http://firmware.ardupilot.org/manifest.json.gz"));
+    downloader->download(QStringLiteral("https://firmware.ardupilot.org/manifest.json.gz"));
 }
 
 void FirmwareUpgradeController::_ardupilotManifestDownloadComplete(QString remoteFile, QString localFile, QString errorMsg)

src/VehicleSetup/FirmwareUpgradeController.h

@@ -226,9 +226,6 @@ private:
     
     QString _firmwareFilename;      ///< Image which we are going to flash to the board
     
-    QNetworkAccessManager*  _downloadManager;       ///< Used for firmware file downloading across the internet
-    QNetworkReply*          _downloadNetworkReply;  ///< Used for firmware file downloading across the internet
-    
     /// @brief Thread controller which is used to run bootloader commands on separate thread
     PX4FirmwareUpgradeThreadController* _threadController;