chore(wmg): improve default wmg cube schema

[atarashansky]

Reason for Change

• Using hilbert ordering for the expression summary default cube was bad for performance once after the WMGv2 changes to the backend. This reverts the schema to be row-ordered like the full expression summary cube.

[codecov]

Codecov Report

Merging #6058 (6799ce9) into main (76a4449) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #6058   +/-   ##
=======================================
  Coverage   90.33%   90.33%           
=======================================
  Files         169      169           
  Lines       13883    13883           
=======================================
  Hits        12541    12541           
  Misses       1342     1342           

Flag	Coverage Δ
unittests	90.33% <ø> (ø)

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Files	Coverage Δ
backend/wmg/data/schemas/cube_schema_default.py	100.00% <ø> (ø)

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[github-actions]

Deployment Summary

• backend_url: https://pr-6058-backend.rdev.single-cell.czi.technology
• frontend_url: https://pr-6058-frontend.rdev.single-cell.czi.technology
• delete_db_task_definition_arn: arn:aws:ecs:us-west-2:***:task-definition/dp-rdev-pr-6058-deletion:1
• migrate_db_task_definition_arn: arn:aws:ecs:us-west-2:***:task-definition/dp-rdev-pr-6058-migration:1