Reenable test variants

[flichtenheld]

The original t_server.sh has different variants of the test triggered by day-of-week. This code is currently commented. Reenable test-variants. Might decide to use a different trigger though?

[cron2]

as originally written this is semi-useful to get more coverage into SSL libraries and options, but it does get in the way (like, mbedTLS builds fail half the tests nowaday as we have legacy ciphers enabled).

So a fresh view on "what variants make sense" and "how to trigger them" sounds like a good plan :)