[Enhancement]: Add the etcd also as part of backup

[kish5430]

What would you like to be added?

The backup tool currently only backs up collection files from the S3 bucket. Its better to add etcd backup along with collections and its indexes.

Why is this needed?

Back tool is not backing up etcd. Milvus restricts root access to etcd, making it impossible to back up. Even if we had root access, it would be preferable to back up etcd along with its collection to save effort and avoid separate backups

Anything else?

No response