The Metaserver node cannot be added or another method is required to add a Metaserver

[YunhuiChen]

Describe the bug (描述bug)
1、The Metaserver machine is down

2、add new metaserver

To Reproduce (复现方法)

Expected behavior (期望行为)

Versions (各种版本)
OS:
Compiler:
curve-mds:
curve-chunkserver:
curve-snapshotcloneserver:
curve-sdk:
nebd:
curve-nbd:

Additional context/screenshots (更多上下文/截图)