explicit config information

[HarrisChu]

Refer https://discuss.nebula-graph.com.cn/t/topic/6333/5

1. currently, show configs just displays mutable configs.
2. and don't display configs per host
3. if local_config is true, the information would make user confused.

it's much more difficult to understand.

prefer:

A: disable show configs, just use the configs in conf file, and use another tool to show and modify conf file directly.
B: or every process report all configs to metad.