Simplify QuantumCircuit._from_circuit_data bit handling

[mtreinish]

Summary

This commit simplifies the logic around bit handling in the QuantumCircuit._from_circuit_data() constructor. Previously it was calling add_bits() for each bit in the CircuitData object to update the output circuit's accounting for each qubit. But this was needlessly heavy as the CircuitData is already the source of truth for the bits in a circuit and we just need to update the indices dictionary. The add_bits() method attempts to add the bits to the CircuitData too but this is wasted overhead because the CircuitData already has the bits as that's where the came from. This changes the constructor to just directly set the bit indices as needed and return the circuit.

Details and comments

[qiskit-bot]

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

• @Qiskit/terra-core

[coveralls]

Pull Request Test Coverage Report for Build 9670599215

Details

• 3 of 4 (75.0%) changed or added relevant lines in 1 file are covered.
• 6 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.01%) to 89.731%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
qiskit/circuit/quantumcircuit.py	3	4	75.0%
<!--	Total:	3	4	75.0%	-->

Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/expr.rs	1	94.02%
crates/qasm2/src/lex.rs	5	91.6%
<!--	Total:	6		-->

Totals
Change from base Build 9661630219:	0.01%
Covered Lines:	63759
Relevant Lines:	71056

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💛 - Coveralls

[mtreinish]

It showed up in py-spy profiling I was doing of permutation synthesis. It wasn't a major component but I was surprised to see it there so I pushed this up to fix it. A dict comprehension is a good idea and will make it a bit faster, I'll tweak this shortly.

[coveralls]

Pull Request Test Coverage Report for Build 9678093460

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
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• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• 21 unchanged lines in 4 files lost coverage.
• Overall coverage increased (+0.02%) to 89.736%

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Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/expr.rs	1	94.02%
qiskit/synthesis/discrete_basis/solovay_kitaev.py	4	94.74%
crates/qasm2/src/lex.rs	6	91.86%
qiskit/providers/fake_provider/generic_backend_v2.py	10	94.71%
<!--	Total:	21		-->

Totals
Change from base Build 9661630219:	0.02%
Covered Lines:	63768
Relevant Lines:	71062

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💛 - Coveralls