Ignore disabled ciphers when deciding if we are using ECC

use_ecc() was always returning 1 because there are default (TLSv1.3)
ciphersuites that use ECC - even if those ciphersuites are disabled by
other options.

Fixes #7471

Reviewed-by: Kurt Roeckx <kurt@roeckx.be>
(Merged from https://github.com/openssl/openssl/pull/7479)