test/run_tests.pl: don't use Module::Load::Conditional.

Ironically enough not all installations get Module::Load::Conditional
installed by default... [It's a bit half-hearted, because such
installations are likely to lack more stuffi that is needed, but
nevertheless, it proved to be helpful.]

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4323)