Before this commit, the compute sequence was relying on the fact the ID was used
as a secondary order key to get the right result.
This is necessary when adding items between pages because we don't resequence
the following elements.
However this was not necessary when adding new elements on the last page since
there are no following elements to resesquence in that case.
PR: #27639
Sébastien Theys
c73efc27b7