SSL test: only write out server2 when testing SNI

SSL test: only write out server2 when testing SNI

The SNI tests introduced a redundant "server2" section into every test
configuration. Copy this automatically from "server" unless testing SNI,
to reduce noise in the generated confs.

Also remove duplicate SSL_TEST_CTX_create (merge conflict error).

Reviewed-by: Rich Salz <rsalz@openssl.org>