Fix/variant removal

[Bloooman]

Context: CiruitOp.Pauli is unnecessary
Summary:
Removed CircuitOp.Pauli from all tests and replace them with CircuitOp.ExpQuatPiPauli if a vairant is necessary for the test
PBCCompiler tests passed after removal
Question: WHat's the purpose of CircuitOp.Prep_Magic? I removed them at this point as they do not fit in my current logic implementation

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.94%. Comparing base (ee5c4cc) to head (d7665a0).

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #11      +/-   ##
==========================================
+ Coverage   78.26%   78.94%   +0.68%     
==========================================
  Files           4        4              
  Lines         184      171      -13     
==========================================
- Hits          144      135       -9     
+ Misses         40       36       -4     

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[Krastanov]

Could you elaborate why this change is useful?