Add ad-hoc edge-case tests to CI

[TysonRayJones]

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[TysonRayJones]

Welp, the 12-qubit statevector unit tests are way too slow to run, even when setting all environment variables to their least intensive. I believe this is because the number of values of numCtrls and numTargs is still very large - though we are really only interested in the settings where numCtrls = numTargs = 6 (and perhaps also where one is <=5 (activating an optimisation) and the other is 6 (no optimisation). We may have to target this specific regime in bespoke TEST_CASE, if possible without duplicating all the operator unit test harness. Bah!

[TysonRayJones]

I've been brainfarting; given the reference state 12-qubit density matrix is intractable (becoming a 24-qubit 256 MiB statevector), so too is the 12-qubit reference operator being attemptedly prepared for multiplication upon the 12-qubit statevector. Regardless of the ctrls + targs permutations, getFullStateOperator() hangs on a 12-qubit state.