* [etcd] Update etcd 3.5.x to 3.6.5
- Add hashes for etcd 3.6.5
- Remove etcd v2 backup task for etcd 3.6
The etcd 3.6 removes 'etcdctl backup' command with ETCDCTL_API=2
- Downgrade etcd to 3.5 in netchecker
The netchecker does not work with etcd 3.6 becaust it removes v2 API support (--enable-v2).
And netchekcer does not support v3 API.
* Fix: Change etcd config to clean up v2 store before upgrading etcd to 3.6
* Bump etcd to 3.6.8
0bfd43499a