Use new setup_tests in code of rsa_test

Although this piece of code will not be compiled at current stage, but
there seems a plan to re-open the 'no-rsa' option in the future so this
should be fixed.

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4161)