MXS-2675: Fix server creation with TLS via REST API

The TLS parameters were defined but the main parameter that enables it
wasn't automatically added. As the REST API documentation states that this
parameter does not need to be defined, the runtime configuration must add
it.

server/core/config_runtime.cc

@@ -1893,6 +1893,11 @@ bool runtime_create_server_from_json(json_t* json)
             {
                 params.set_multiple(extract_parameters_from_json(json));
 
+                if (params.contains_any({CN_SSL_KEY, CN_SSL_CERT, CN_SSL_CA_CERT}))
+                {
+                    params.set(CN_SSL, "true");
+                }
+
                 if (Server* server = Server::server_alloc(name, params))
                 {
                     if (link_server_to_objects(server, relations) && server->serialize())