fix: BulkConcurrentObservableCollection::Remove returns false if item not found (#9345)

Author: jiejasonliu

src/Files.Uwp/Helpers/ItemListDisplayHelpers/BulkConcurrentObservableCollection.cs

@@ -283,7 +283,7 @@ public bool Remove(T item)
 
                 if (index == -1)
                 {
-                    return true;
+                    return false;
                 }
 
                 collection.RemoveAt(index);