Fix setting TLS groups with BoringSSL

[masaori335]

I found that SSLMultiCertConfigLoader::_set_curves function is not working as expected with BoringSSL. Because this check doesn't work with BoringSSL, because it's defined as a function instead of macro.

#if defined(SSL_CTX_set1_groups_list) || defined(SSL_CTX_set1_curves_list)

[maskit]

No duplicate code please.

[masaori335]

The SSL_CTX_set1_groups_list function is introduced by OpenSSL 1.1.1, and that is ATS 10's minimum supported version.
Thus, we just don't need these ifdefs, I think.

For 9.2.x branch, I'll open another PR.

Looks good