* [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
This uses the same logic than the other versions, with simplications for
crictl and crio whose versionning scheme is tied to upstream kubernetes.
Also move some version variables in vars/ rather than defaults/, because
they are not used elsewhere and don't really make sense as modifiable by
the user.
The checksums are not a defaults and are not meant to be changed from
the inventories.
Furthermore, role defaults have a lower priority that hosts facts, which
technically means a rogue hosts could hijack the hashes for its
variables.
