rand: add set0 calls for the private and public DRBGs

rand: add set0 calls for the private and public DRBGs

The FIPS 140-3 DSA and ECDSA tests need to be known answer tests which means
the entropy needs to be cooked.  This permits this.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/19510)