WL#13289: Remove yaSSL support from 5.6/5.7 codebase

Affects: Server-8.0   —   Status: Complete

We're no longer going to build or test 5.6 and 5.7 with yaSSL.
This is a worklog to remove yaSSL and the support for it in the code and cmake
from 5.6 and 5.7 trees.