(#17864) Don't check certificate_revocation if configured not to
(maint) Refactor ssl/host_spec.rb crl context

The tests added in 81a5cbb added more checks around the
certificate_revocation setting and overrided the local context settings.
This commit splits the rspec context into two smaller contexts for each
possible case and sets values in the before block accordingly.
Merge branch 'pull-1504'

This closes GH-1504.