Remove host option from ServerConfig proto since it is error-prone and

src/node/performance/worker_service_impl.js

src/proto/grpc/testing/control.proto

test/cpp/qps/async_streaming_ping_pong_test.cc

test/cpp/qps/async_unary_ping_pong_test.cc

test/cpp/qps/generic_async_streaming_ping_pong_test.cc

test/cpp/qps/qps_driver.cc

test/cpp/qps/qps_openloop_test.cc

test/cpp/qps/qps_test.cc

test/cpp/qps/qps_test_with_poll.cc

test/cpp/qps/secure_sync_unary_ping_pong_test.cc

test/cpp/qps/server_async.cc

test/cpp/qps/server_sync.cc

test/cpp/qps/sync_streaming_ping_pong_test.cc

test/cpp/qps/sync_unary_ping_pong_test.cc