Treat classically controlled ops as non-Clifford in dynamical_decoupling

[p51lee]

Classically controlled operations were passing _is_clifford_op, which led dynamical_decoupling to synthesize/invert through them and crash. Mark them non-Clifford for DD so they act as boundaries. Add regression test test_classically_controlled_no_update_succeeds.

Fixes #7617

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.38%. Comparing base (12b3906) to head (5c94b70).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7621   +/-   ##
=======================================
  Coverage   99.38%   99.38%           
=======================================
  Files        1091     1091           
  Lines       97901    97907    +6     
=======================================
+ Hits        97295    97301    +6     
  Misses        606      606           

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[daxfohl]

lgtm

[babacry]

Thanks for the fix! Clifford op indeed should be checked with the additional condition.

[p51lee]

Hi @vtomole @95-martin-orion,
This PR has approvals and all checks are passing — could you please take a look when you have a moment? Thanks!

[95-martin-orion]

I've been away from Cirq too long to provide a good review - leaving this to @vtomole.