remove unuse config

Former-commit-id: d426be7162d79534f9a992118da4d4e979c55662

cpp/conf/server_config.yaml

 server_config:
   address: 0.0.0.0
   port: 19530
-  transfer_protocol: binary   #optional: binary, compact, json
-  server_mode: thread_pool    #optional: simple, thread_pool
   gpu_index: 0                #which gpu to be used
   mode: single                #optional: single, cluster