When ordering by a column and partitioning by another, we must reset the
peer_tracker for dense_rank, regardless if the value for the order
column changes or not.

Example:
select a, b, dense_rank() over (partition by b order by a)
a  |  b  |  dense_rank
----------------------
1  | p1  |           1
2  | p1  |           2
2  | p2  |           1   // Here, without this fix we returned 0.
2  | p2  |           2   // And 1 here.