Refactor build.yml CI ssltests config and multissltests.py

[WillChilds-Klein]

Feature or enhancement

Proposal:

Following up on #135401, this issue tracks the refactoring follow-ups summarized here.

Has this already been discussed elsewhere?

I have already discussed this feature proposal on Discourse

Links to previous discussion of this feature:

#135402 (comment)
#135401
https://discuss.python.org/t/support-building-ssl-and-hashlib-modules-against-aws-lc/44505/14

Linked PRs

• gh-136728: Refactor build.yml CI config and multissltests.py #136729