remove unuse config

Former-commit-id: dad8d4734bb4344d7999a74cdbef9a0eb8781daf

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