Do not deepcopy operations in Unroll3qOrMore (#10702)

In the Unroll3qOrMore pass internally is quite simple it iterates over
every operation in the circuit and for any operation that uses >= 3
qubits and recursively decompsing it into all 1 and 2 qubit operations,
converting it to a DAGCircuit and substituting the >=3 qubit gates with
the equivalent circuit. However, during this DAGCircuit conversion step
we're spending a large amount deep copying the operation objects.
However, we don't need to do this because nothing in the circuit will be
reused with shared references so we can skip the copying and just pass
the operation objects by reference onto the DAG (as that's all we need).
This commit makes that change by using the `copy_operations` flag we
introduced in #9848 on circuit_to_dag() to disable the internal copying.

qiskit/transpiler/passes/basis/unroll_3q_or_more.py

@@ -80,7 +80,7 @@ def run(self, dag):
                     "Cannot unroll all 3q or more gates. "
                     "No rule to expand instruction %s." % node.op.name
                 )
-            decomposition = circuit_to_dag(node.op.definition)
+            decomposition = circuit_to_dag(node.op.definition, copy_operations=False)
             decomposition = self.run(decomposition)  # recursively unroll
             dag.substitute_node_with_dag(node, decomposition)
         return dag