Clean up preprocess and pass correct gate set

[astralcai]

Context:

• Update the preprocess transforms to pass the correct gate set to decompose.
• Clean up duplicate code in the preprocess transforms.

Description of the Change:

Benefits:

Possible Drawbacks:

Related GitHub Issues:
[sc-110772]

[github-actions]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.62%. Comparing base (7d89251) to head (93ea3b3).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1341      +/-   ##
==========================================
+ Coverage   95.79%   96.62%   +0.83%     
==========================================
  Files         243      307      +64     
  Lines       40533    47342    +6809     
==========================================
+ Hits        38829    45746    +6917     
+ Misses       1704     1596     -108     

Flag	Coverage Δ
unit_tests	96.62% <100.00%> (+0.83%)	⬆️

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[LuisAlfredoNu]

Thanks @astralcai
Could you trigger the CIs again to check that the LG and LK pass the tests, please?

[LuisAlfredoNu]

Thank you @astralcai
LGTM

[maliasadi]

LGTM! My only remaining concern #1341 (comment) is unrelated to this PR and requires further discussion.