Fix replace_block_with_op on operations with wrong number of qubits (backport #12637)

[mergify]

Summary

Previously, DAGCircuit.replace_block_with_op allowed to place an
n-qubit operation onto a block of m qubits, leaving the DAG in an
invalid state. This behavior has been fixed, and the attempt will raise
a DAGCircuitError.

Details and comments

For example, this is currently possible:

from qiskit import transpile
from qiskit.circuit import QuantumCircuit
from qiskit.converters import circuit_to_dag, dag_to_circuit
from qiskit.circuit.library import XGate

# i am fine
qc = QuantumCircuit(2)
qc.x(range(2))

# a bit of dag mutilation
dag = circuit_to_dag(qc)
to_replace = list(dag.op_nodes())
new_node = XGate()
idx_map = {node.qargs[0]: i for i, node in enumerate(to_replace)}
dag.replace_block_with_op(to_replace, new_node, idx_map)

# the result
midlifecrisis = dag_to_circuit(dag)
print(midlifecrisis)

# naturally breaks
tqc = transpile(midlifecrisis, basis_gates=["u", "cx"])
print(tqc)

which prints

     ┌────┐
q_0: ┤0   ├
     │  X │
q_1: ┤1   ├
     └────┘
# and then breaks upon transpilation

---

This is an automatic backport of pull request #12637 done by [Mergify](https://mergify.com).

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[coveralls]

Pull Request Test Coverage Report for Build 9747108484

Details

• 3 of 3 (100.0%) changed or added relevant lines in 2 files are covered.
• 15 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.01%) to 87.202%

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Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/lex.rs	3	92.88%
crates/qasm2/src/parse.rs	12	97.15%

Totals
Change from base Build 9687482615:	-0.01%
Covered Lines:	74520
Relevant Lines:	85457

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💛 - Coveralls