Fix behavior for finding position from index (#1344)
Fix behavior for finding position from index (#1344)

This commit fixes a leftover piece of behavior from when we were using
the json transpile to find the qubit register name and bit number from a
raw qubit index number (the qubit number from the top across all
registers). The function doing this conversion was incorrectly assuming
the bit numbers always increased as it iterated over the register, which
is not true in all cases. But, either way it's made unnecessary now
because the operations list from the dag/circuit returns the actual
register name and bit number in the register. So this step isn't needed
anymore and this commit removes it and fixes any operations that were
using this, thereby fixing any ordering errors on those operations.

Fixes #1342
QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py,QISKit/qiskit-sdk-py