Qiskit / qiskit / 26644652977

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Use TwoQubitPeepholeOptimization in preset pass managers (#16136)

* Use TwoQubitPeepholeOptimization in preset pass managers

Following on from #13419 which added a new optimization pass
TwoQubitPeepholeOptimization which was designed to replace the
pair of ConsolidateBlocks and UnitarySynthesis for the optimization
stage after we have a physical circuit. That PR however did not update
the preset pass managers to concentrate the review on just adding the
new pass. This continues off from there by updating the preset pass
managers to use the new pass in optimization levels 2 and 3 replacing
those levels' optimization stage's previous usage of ConsolidateBlocks
and UnitarySynthesis to achieve the same goal. This should result in
both a runtime performance and transpilation quality improvement as the
new pass is both faster and should produce better fidelity circuits
than the previous peephole optimization.

The tests updates that are made in this PR are because the peephole
optimization is changing the transpilation output of various test
circuits. These were all verified to be valid outputs and in all cases
a "better" output than before. Specifically, for the tests updated
these were the changes in output and why they occurred:

* The two tests in
  test.python.circuit.test_scheduled_circuit.TestScheduledCircuit were
  the single CX gate in the output circuit was flipped from (0, 1) to
  (1, 0) because in the target the error rate for the (0, 1) direction
  was higher than the extra error cost of 3 sx gates (the rz gates have
  0 error).
* In test_unroll_only_if_not_gates_in_basis from
  test.python.transpiler.test_preset_passmanagers.TestPresetPassManager
  we no longer run ConsolidateBlocks in the optimization loop so we no
  longer need to add the 2 executions from the init and translation
  stages. The test is updated to count the new peephole pass which is
  the intent of the count check, to check the pass in the optimization
  loop.
* In test_2q... (continued)

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7 existing lines in 2 files now uncovered.

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