Rewrite tests for split_non_commuting

[astralcai]

This is an attempt to refactor the tests for one of the transforms, hoping to set a standard for future transform tests. For each transform, we should have:

• Unit tests for basic functionalities of the transform:
  • Does the transform produce the correct tapes?
  • Does the processing function return the correct results (numerical correctness tested here)?
• Tests for integration of the transform with a QNode:
  • Tests different combinations of parameter broadcasting and shots/shot-vectors
  • Mainly tests that the circuit executes without error and returns results with the correct shapes.
• Tests for the differentiability of QNodes with this transform applied:
  • Tests different interfaces
  • Tests numerical correctness of the gradients

[sc-72000]
[sc-72519]

[github-actions]

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Please edit doc/releases/changelog-dev.md with:

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.62%. Comparing base (0aa4738) to head (fd157b9).
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #6687    +/-   ##
========================================
  Coverage   99.61%   99.62%            
========================================
  Files         473      474     +1     
  Lines       44355    44617   +262     
========================================
+ Hits        44186    44448   +262     
  Misses        169      169            

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[mlxd]

Thanks @astralcai

A few questions from my side:

[mlxd]

Many previous questions resolved without comment. Same questions/prompts apply.