_ssl.c calls SSL_CTX_get_verify_callback unnecessarily

[davidben]

Bug report

Bug description:

I'll upload a PR shortly for a small bit of cleanup. The PR template wants a GitHub issue, so this is that.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-113332: Simplify calls to SSL_(CTX_)set_verify in _ssl.c #113333