fix: support scaling up/down etcd

[redscholar]

What type of PR is this?

/kind feature

What this PR does / why we need it:

Should support etcd scaling:

• scaling up etcd:

1. Define the etcd nodes in inventory.yaml.

apiVersion: kubekey.kubesphere.io/v1
kind: Inventory
metadata:
  name: default
spec:
  hosts: # your can set all nodes here. or set nodes on special groups.
    node1:
      connector:
        host: 172.16.66.7
      internal_ipv4: 172.16.66.7
    node2:
      connector:
        host: 172.16.66.3
      internal_ipv4: 172.16.66.3
    node3:
      connector:
        host: 172.16.66.4
      internal_ipv4: 172.16.66.4
  groups:
    # all kubernetes nodes.
    k8s_cluster:
      groups:
        - kube_control_plane
        - kube_worker
    # control_plane nodes
    kube_control_plane:
      hosts:
        - node1
    # worker nodes
    kube_worker:
      hosts:
        - node1
    # etcd nodes when etcd_deployment_type is external
    etcd:
      hosts:
        - node1

2. Create cluster by this inventory.yaml
   kk create cluster -i inventory.yaml
3. Add etcd node in inventory.yaml

apiVersion: kubekey.kubesphere.io/v1
kind: Inventory
metadata:
  name: default
spec:
  hosts: # your can set all nodes here. or set nodes on special groups.
    node1:
      connector:
        host: 172.16.66.7
      internal_ipv4: 172.16.66.7
    node2:
      connector:
        host: 172.16.66.3
      internal_ipv4: 172.16.66.3
    node3:
      connector:
        host: 172.16.66.4
      internal_ipv4: 172.16.66.4
  groups:
    # all kubernetes nodes.
    k8s_cluster:
      groups:
        - kube_control_plane
        - kube_worker
    # control_plane nodes
    kube_control_plane:
      hosts:
        - node1
        - node2
        - node3
    # worker nodes
    kube_worker:
      hosts:
        - node1
        - node2
        - node3
    # etcd nodes when etcd_deployment_type is external
    etcd:
      hosts:
        - node1
        - node2
        - node3

4. Scaling up etcd.
   kk add nodes -i inventory.yaml

• scaling down etcd:

1. Define the etcd nodes in inventory.yaml.

apiVersion: kubekey.kubesphere.io/v1
kind: Inventory
metadata:
  name: default
spec:
  hosts: # your can set all nodes here. or set nodes on special groups.
    node1:
      connector:
        host: 172.16.66.7
      internal_ipv4: 172.16.66.7
    node2:
      connector:
        host: 172.16.66.3
      internal_ipv4: 172.16.66.3
    node3:
      connector:
        host: 172.16.66.4
      internal_ipv4: 172.16.66.4
  groups:
    # all kubernetes nodes.
    k8s_cluster:
      groups:
        - kube_control_plane
        - kube_worker
    # control_plane nodes
    kube_control_plane:
      hosts:
        - node1
        - node2
        - node3
    # worker nodes
    kube_worker:
      hosts:
        - node1
        - node2
        - node3
    # etcd nodes when etcd_deployment_type is external
    etcd:
      hosts:
        - node1
        - node2
        - node3

2. Create cluster by this inventory.yaml
   kk create cluster -i inventory.yaml
3. Scaling down etcd
   kk delete nodes -i inventory.yaml node2 node3

test results

Which issue(s) this PR fixes:

Fixes #
#2728
#2742

Special notes for reviewers:

Does this PR introduced a user-facing change?

fix: support scaling down etcd

Additional documentation, usage docs, etc.:

[sonarqubecloud]

Quality Gate failed

Failed conditions
1 Security Hotspot

See analysis details on SonarQube Cloud