Remove etcdutl backup command

[geetasg]

Bug report criteria

• This bug report is not security related, security issues should be disclosed privately via [email protected].
• This is not a support request, support requests should be raised in the etcd discussion forums.
• You have read the etcd bug reporting guidelines.
• Existing open issues along with etcd frequently asked questions have been checked and this is not a duplicate.

What happened?

From some of the code review discussions in #16132, it seems like etcdutl backup command should be removed in 3.6. (etcdutl/etcdutl/backup_command.go)

This issue is meant to -

• Confirm that the command needs to be removed.
• if so then , communicate with the user base that the command will be removed in 3.6 and remove it.

What did you expect to happen?

command should not be there if it is not used anymore.

How can we reproduce it (as minimally and precisely as possible)?

Usage:
etcdutl [command]

Available Commands:
backup [legacy] offline backup of etcd directory
completion Generate completion script
defrag Defragments the storage of the etcd
help Help about any command
migrate Migrates schema of etcd data dir files to make them compatible with different etcd version
snapshot Manages etcd node snapshots
version Prints the version of etcdutl

Remove the backup command if it should not be there in 3.6

Anything else we need to know?

Also discussed at #16132

Etcd version (please run commands below)

$ etcd --version
# paste output here
etcd Version: 3.6.0-alpha.0
Git SHA: fac4102ab
Go Version: go1.20.4

$ etcdctl version
# paste output here

etcdctl version: 3.6.0-alpha.0
API version: 3.6

Etcd configuration (command line flags or environment variables)

paste your configuration here

Etcd debug information (please run commands below, feel free to obfuscate the IP address or FQDN in the output)

$ etcdctl member list -w table
# paste output here

$ etcdctl --endpoints=<member list> endpoint status -w table
# paste output here

Relevant log output

No response

[basit9958]

I will look into this.
/assign

[jmhbnz]

Fixed in #16662.