Deepcopy BoxOp bodies when copying circuits (backport #14918)

[mergify]

Changes:

• Updated the instruction deep-copy logic so copying a circuit now recursively clones its parameters, ensuring BoxOp bodies are duplicated instead of shared between the original and the copy.
• Added a test to verify that copying a circuit containing a BoxOp produces an independent body that can be mutated without affecting the original circuit.

Why?

• Fixes QuantumCircuit.copy does not deepcopy contents of BoxOp #14501

---

This is an automatic backport of pull request #14918 done by [Mergify](https://mergify.com).

[qiskit-bot]

Thank you for opening a new pull request.

Before your PR can be merged it will first need to pass continuous integration tests and be reviewed. Sometimes the review process can be slow, so please be patient.

While you're waiting, please feel free to review other open PRs. While only a subset of people are authorized to approve pull requests for merging, everyone is encouraged to review open pull requests. Doing reviews helps reduce the burden on the core team and helps make the project's code better for everyone.

One or more of the following people are relevant to this code:

• @Qiskit/terra-core

[coveralls]

Pull Request Test Coverage Report for Build 18391418026

Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• 26 unchanged lines in 4 files lost coverage.
• Overall coverage decreased (-0.01%) to 88.391%

---

Files with Coverage Reduction	New Missed Lines	%
crates/qasm2/src/expr.rs	1	93.63%
crates/qasm2/src/lex.rs	4	92.27%
crates/circuit/src/parameter/symbol_expr.rs	9	72.9%
crates/qasm2/src/parse.rs	12	97.09%

Totals
Change from base Build 18354852432:	-0.01%
Covered Lines:	92300
Relevant Lines:	104422

---

💛 - Coveralls