Remove unused type aliases (#17396)

This PR eliminates unused type aliases in join details.

Authors:
  - Yunsong Wang (https://github.com/PointKernel)

Approvers:
  - Nghia Truong (https://github.com/ttnghia)
  - David Wendt (https://github.com/davidwendt)
  - Bradley Dice (https://github.com/bdice)

URL: #17396

cpp/src/join/join_common_utils.hpp

@@ -50,11 +50,6 @@ using mixed_multimap_type =
                         cudf::detail::cuco_allocator<char>,
                         cuco::legacy::double_hashing<1, hash_type, hash_type>>;
 
-using row_hash_legacy =
-  cudf::row_hasher<cudf::hashing::detail::default_hash, cudf::nullate::DYNAMIC>;
-
-using row_equality_legacy = cudf::row_equality_comparator<cudf::nullate::DYNAMIC>;
-
 bool is_trivial_join(table_view const& left, table_view const& right, join_kind join_type);
 }  // namespace detail
 }  // namespace cudf