Fix the traits order computations for clustering

Issue:
https://github.com/genenetwork/gn-gemtext-threads/blob/main/topics/gn1-migration-to-gn2/clustering.gmi

* gn3/computations/heatmap.py: Fix ordering function
* tests/unit/computations/test_heatmap.py: update test

  The order of the traits is important for the clustering algorithm, since the
  clustering seems to use the distance of one trait from another to determine
  how to order them.

  This commit also gets rid of the xoffset argument that is not important to
  the ordering, and was used in the older GN1 to determine how to draw the
  clustering lines.

0 files changed, 0 insertions, 0 deletions