Fix clazy QFileInfo::exists warnings

Author: nyalldawson

src/analysis/processing/qgsalgorithmfiledownloader.cpp

@@ -88,7 +88,7 @@ QVariantMap QgsFileDownloaderAlgorithm::processAlgorithm( const QVariantMap &par
   loop.exec();
 
   timer.stop();
-  bool exists = QFileInfo( outputFile ).exists();
+  bool exists = QFileInfo::exists( outputFile );
   if ( !feedback->isCanceled() && !exists )
     throw QgsProcessingException( tr( "Output file doesn't exist." ) );
 

tests/src/gui/testqgsfiledownloader.cpp

@@ -250,7 +250,7 @@ void TestQgsFileDownloader::testLacksWritePermissionsError()
   QVERIFY( !mCompleted );
   QVERIFY( mError );
   QVERIFY( !mCanceled );
-  QVERIFY( ! QFileInfo( fileName ).exists( ) );
+  QVERIFY( ! QFileInfo::exists( fileName ) );
 }