Fix: Incorrect initialization of BackendV2 for transpiler_level ASV Test

[raynelfss]

Summary

After the removal of BackendV1 in #13793, and the prospective updates done by #13805, the transpiler_level tests are no longer working due to an erroneous initialization of a GenericBackendV2 in which the number of qubits on the backend did not match the number of qubits in the coupling map. The following commits fix said issue by ensuring both of these parameters match.

[qiskit-bot]

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

• @Qiskit/terra-core

[mtreinish]

Thanks for fixing this. We've been missing the data from these benchmarks for some time so it'll be good to fix this. I ran asv locally and confirmed it fixes the run too.

[coveralls]

Pull Request Test Coverage Report for Build 14202490169

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 4 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.02%) to 88.074%

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Files with Coverage Reduction	New Missed Lines	%
crates/accelerate/src/unitary_synthesis.rs	1	94.79%
crates/qasm2/src/lex.rs	3	92.98%

Totals
Change from base Build 14202044040:	0.02%
Covered Lines:	72821
Relevant Lines:	82682

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💛 - Coveralls