nodetool: use exact intersect when picking features (fixes #15294)

(cherry picked from commit 6b27994)

Author: jef-n

src/app/nodetool/qgsmaptoolnodetool.cpp

@@ -201,6 +201,7 @@ QgsFeature QgsMapToolNodeTool::getFeatureAtPoint( QgsMapMouseEvent* e )
 
   QgsFeatureRequest request;
   request.setFilterRect( QgsRectangle( e->mapPoint().x(), e->mapPoint().y(), e->mapPoint().x(), e->mapPoint().y() ) );
+  request.setFlags( QgsFeatureRequest::ExactIntersect );
   QgsFeatureIterator features = vlayer->getFeatures( request );
   features.nextFeature( feature );