In rand_cleanup_int(), don't go creating a default method

If no default method was yet given, RAND_get_rand_method() will set it
up.  Doing so just to clean it away seems pretty silly, so instead,
use the default_RAND_meth variable directly.

This also clears a possible race condition where this will try to init
things, such as ERR or ENGINE when in the middle of a OPENSSL_cleanup.

Fixes #3128

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3136)
(cherry picked from commit 5006b37b)