Reduce app ID hardcoding

And rename the relevant build variable to make more sense

Signed-off-by: Echo J <tcg96nougat@gmail.com>

launcher/Application.cpp

@@ -225,7 +225,7 @@ Application::Application(int& argc, char** argv) : QApplication(argc, argv)
     setApplicationName(BuildConfig.LAUNCHER_NAME);
     setApplicationDisplayName(QString("%1 %2").arg(BuildConfig.LAUNCHER_DISPLAYNAME, BuildConfig.printableVersionString()));
     setApplicationVersion(BuildConfig.printableVersionString() + "\n" + BuildConfig.GIT_COMMIT);
-    setDesktopFileName(BuildConfig.LAUNCHER_DESKTOPFILENAME);
+    setDesktopFileName(BuildConfig.LAUNCHER_APPID);
     m_startTime = QDateTime::currentDateTime();
 
     // Don't quit on hiding the last window
@@ -1949,4 +1949,4 @@ bool Application::checkQSavePath(QString path)
         }
     }
     return false;
-}
+}