Fix random_clifford

[alexanderivrii]

Summary

Fixes #13590.

Details and comments

The bug was introduced when porting random_clifford to Rust in #12695.

I have added tests that ensure that for 2-qubits Cliffords, random_clifford produces Cliffords with all possible symplectic matrices (there should be 720) and all possible CX counts (should be {0, 1, 2, 3}). @ShellyGarion, can you think of other tests that we may wish to add?

[qiskit-bot]

One or more of the following people are relevant to this code:

• @Qiskit/terra-core

[ShellyGarion]

Thanks @alexanderivrii for fixing this bug!
The tests for 2-qubit Cliffords look good to me.
I wonder if we can also test larger Cliffrods, say with 3 and 4 qubits. We can't check that we generate the entire group (it's just too large), but perhaps we can check that they produce distinct CX counts?

[coveralls]

Pull Request Test Coverage Report for Build 12503720653

Details

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• 12 unchanged lines in 4 files lost coverage.
• Overall coverage increased (+0.002%) to 88.953%

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Files with Coverage Reduction	New Missed Lines	%
crates/accelerate/src/two_qubit_decompose.rs	1	92.13%
crates/accelerate/src/unitary_synthesis.rs	1	92.2%
crates/qasm2/src/lex.rs	4	92.48%
crates/qasm2/src/parse.rs	6	97.62%

Totals
Change from base Build 12420636821:	0.002%
Covered Lines:	79429
Relevant Lines:	89293

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💛 - Coveralls