MCOL-5114 Removing ctor specialization b/c it violates c++20 syntax needed in ColumnStorew

sql/item_cmpfunc.h

@@ -3450,7 +3450,7 @@ template <template<class> class LI, typename T> class Item_equal_iterator
   Item_equal *item_equal;
   Item *curr_item;
 public:
-  Item_equal_iterator<LI,T>(Item_equal &item_eq) 
+  Item_equal_iterator(Item_equal &item_eq)
     :LI<T> (item_eq.equal_items)
   {
     curr_item= NULL;