Remove deprecated methods and arguments in quantum_info

[ikkoham]

Summary

Details and comments

[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 the following people are requested to review this:

• @Qiskit/terra-core
• @ikkoham

[mtreinish]

Thanks for cleaning up old deprecations, I had one question inline. Also this needs an upgrade release note documenting the removal

[coveralls]

Pull Request Test Coverage Report for Build 2969607909

• 3 of 3 (100.0%) changed or added relevant lines in 2 files are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.001%) to 84.148%

---

Files with Coverage Reduction	New Missed Lines	%
qiskit/extensions/quantum_initializer/squ.py	2	79.78%

Totals
Change from base Build 2967364302:	-0.001%
Covered Lines:	57008
Relevant Lines:	67747

---

💛 - Coveralls