tiup cluster prune <cluster name> don't work

[Tammyxia]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

• scale-in two tikv, till they become Tomestone status.
• tiup cluster prune

2. What did you expect to see?
   The two scaled-in TiKV disappeared in tiup cluster display

3. What did you see instead?

• The two scaled-in TiKV still visible in tiup cluster display

• tiup cluster log in ~/.tiup/logs/tiup-cluster-debug-xxx.log has not any log about command "tiup cluster prune xxx"

4. What version of TiUP are you using (tiup --version)?

[root@localhost logs]# tiup --version
1.7.0 tiup
Go Version: go1.17.3
Git Ref: v1.7.0
GitHash: ce8eb0a
[root@localhost logs]# tiup cluster --version
Starting component cluster: /root/.tiup/components/cluster/v1.8.0/tiup-cluster --version
tiup version 1.8.0 tiup
Go Version: go1.17.3
Git Ref: v1.8.0
GitHash: ff08d40

[AstroProfundis]

This seems a dupe w/ #1148

If the scale-in operation was not fully finished (so that the offline mark in meta.yaml is not set), the prune command will not delete the node. We can optimize this behavior.

[AstroProfundis]

On OP's cluster, the prune is not working correctly even if the offline: true flag is manually added to meta.yaml, and that's because PD has changed their API response in nightly build, so that the State field is always 0 and be assumed as "Up".

We'll discuss with PD team about this potential compatibility breaking change.