Call RAND_DRBG_bytes from inside the FIPS provider

Insert a dummy call to RAND_DRBG_bytes from inside the FIPS provider to
demonstrate that it is possible to use the RAND code from inside the
module. This is temporary and will be removed once real uses of the RAND
code are available inside the module.

Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/9035)