Improve qubit scaling of CalibrationBuilder (#7187)
Improve qubit scaling of CalibrationBuilder (#7187)

There is potential further work to add a full find_bit method into
DAGCircuit, which in the future could replace the dictionary
comprehension used in this PR, but as things stands, this removes an
inner loop (via `list.index`) to reduce the polynomial complexity.

Co-authored-by: mergify[bot] <b09a6ee808b67e98a221404e7aaa52e0398a4954@users.noreply.github.com>
QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py