Don't query list of visible features when showing selected features

On behalf of Faunalia, sponsored by ENEL

(cherry-picked from 5346023)

src/gui/attributetable/qgsattributetablefiltermodel.cpp

@@ -292,11 +292,6 @@ void QgsAttributeTableFilterModel::setFilterMode( FilterMode filterMode )
       disconnect( mCanvas, SIGNAL( extentsChanged() ), this, SLOT( extentsChanged() ) );
     }
 
-    if ( filterMode == ShowSelected )
-    {
-      generateListOfVisibleFeatures();
-    }
-
     mFilterMode = filterMode;
     invalidateFilter();
   }
@@ -350,7 +345,6 @@ void QgsAttributeTableFilterModel::selectionChanged()
 {
   if ( ShowSelected == mFilterMode )
   {
-    generateListOfVisibleFeatures();
     invalidateFilter();
   }
   else if ( mSelectedOnTop )