Remove Trifunctor Hierarchy (#2026)

[neko-kai]

See #2026

[codecov-commenter]

Codecov Report

Merging #2027 (e1792dc) into develop (367b38d) will increase coverage by 0.69%.
The diff coverage is 45.05%.

❗ Current head e1792dc differs from pull request most recent head 95a7602. Consider uploading reports for the commit 95a7602 to get more accurate results

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@@             Coverage Diff             @@
##           develop    #2027      +/-   ##
===========================================
+ Coverage    65.41%   66.11%   +0.69%     
===========================================
  Files          558      546      -12     
  Lines        11168    10925     -243     
===========================================
- Hits          7306     7223      -83     
+ Misses        3862     3702     -160