[Release-1.31] - Add a guardrail for etcd-snapshot

[manuelbuil]

Backport fix for Add a guardrail for etcd-snapshot

• Add a guardrail for etcd-snapshot #11388

[VestigeJ]

Reproduced way back here - #11388 (comment)

$ k3s etcd-snapshot save

WARN[0000] Unknown flag --node-ip found in config.yaml, skipping
WARN[0000] Unknown flag --write-kubeconfig-mode found in config.yaml, skipping
WARN[0000] Unknown flag --token found in config.yaml, skipping
FATA[0000] open /home/ec2-user/.rancher/k3s/server/token: no such file or directory

$ sudo /usr/local/bin/k3s etcd-snapshot save

WARN[0000] Unknown flag --node-ip found in config.yaml, skipping
WARN[0000] Unknown flag --write-kubeconfig-mode found in config.yaml, skipping
WARN[0000] Unknown flag --token found in config.yaml, skipping
FATA[0000] see server log for details: etcd datastore disabled

$ k3s -v

k3s version v1.31.5+k3s-39b54b9f (39b54b9f)
go version go1.22.10