Don't set default ciphers for OpenSSL client sockets

It should be up to the OS to set the default ciphers, eg. if a cipher
suddenly is deemed insecure or there's a reason to have another cipher
order, such as ChaCha over any AES cipher because of lack of hardware
support.

Currently Crystal will expose up-to-date OS to security considirations
because of hard coded cipher lists, that might not be so up to date,
unless the application is recompiled with a modern Crystal version.

src/openssl/ssl/context.cr

@@ -49,8 +49,6 @@ abstract class OpenSSL::SSL::Context
       {% if LibSSL.has_method?(:x509_verify_param_lookup) %}
         self.default_verify_param = "ssl_server"
       {% end %}
-
-      self.ciphers = CIPHERS_OLD
     end
 
     # Returns a new TLS client context with only the given method set.