[Improvement] add more environment for lifecycleAction

[loomts]

Is your improvement request related to a problem? Please describe.
It is better to get $PEER_FQDNS to specify all node addresses in the etcd cluster using the --endpoints option when using the etcdctl command.
It's good for switchover and may also useful in memberJoin, memberLeave etc.

Additional context

[loomts]

kbagent agent can use env from configmap, close this issue.