Remove session checks from SSL_clear()

We now allow a different protocol version when reusing a session so we can
unconditionally reset the SSL_METHOD if it has changed.

Reviewed-by: Ben Kaduk <kaduk@mit.edu>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/3954)