DSA_generate_parameters_ex: use the old method for all small keys
DSA_generate_parameters_ex: use the old method for all small keys

Fixes #14733

Reviewed-by: Paul Dale <ddec78389666b4f7c9b4d110380c848489a3e4aa@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14744)

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl