add support for provisioning idempotency when using external data source

[xunkutech]

Proposed Changes

When we use an external data source instead of etcd, we have the possibility to archive idempotency for the initialization of the cluster. The only problem is that we have to keep the random node password of the nodes for rejoining. Considering the security, we use {{ node_password_salt + ansible_hostname | md5 }} as the invariant node password for each node. After that, the nodes can be re-registered to the cluster when the cluster is reinitialized by this playbook.

Checklist

• [ ] Tested locally
• [ ] Ran site.yml playbook
• [ ] Ran reset.yml playbook
• [ ] Did not add any unnecessary changes
• [ ] Ran pre-commit install at least once before committing
• [ ] 🚀

[timothystewart6]

Going to close this for now since we haven't seen any activity. Feel free to reopen the PR after the items are addressed. Thank you!