A connection error occurs when etcd is not configured with cert

[rxy0210]

Expected Behavior

If you do not configure the cert file, you can connect to etcd for access

Current Behavior

Unable to connect to etcd

Possible Solution

Set tls to nil

Steps to Reproduce (for bugs)

1. When I run the above unit test, the following error is reported when I try to connect to the CERt-free etcd.

func createEtcdClient() (api.Client, error) {
	etcdConfig := apiconfig.EtcdConfig{
		EtcdEndpoints: "127.0.0.1:2379",
	}
	etcdV3Client, err := etcdv3.NewEtcdV3Client(&etcdConfig)
	if err != nil {
		return nil, err
	}
	return etcdV3Client, nil
}

func TestEtcdV3Client(t *testing.T) {
	tests := []struct {
		name        string
		cidr        string
		nodeName    string
		expectValue model.BlockAffinity
	}{
		{
			name:     "test1",
			cidr:     "1.1.1.1/26",
			nodeName: "node1",
			expectValue: model.BlockAffinity{
				State:   "confirmed",
				Deleted: false,
			},
		},
	}

	cli, err := createEtcdClient()
	if err != nil {
		t.Errorf("connect to etcd failed, err:%v\n", err)
	}
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			_, cidr, err := net.ParseCIDR(test.cidr)
			if err != nil {
				t.Fatalf("Failed to parse CIDR: %v", err)
			}
			key := model.BlockAffinityKey{
				Host: test.nodeName,
				CIDR: *cidr,
			}
			get, err := cli.Get(ctx, key, "")
			if err != nil {
				fmt.Printf("create from etcd failed, err:%v\n", err)
				return
			}
			value, ok := get.Value.(*model.BlockAffinity)
			if !ok {
				t.Errorf("Value is not BlockAffinity, err:%v\n", err)
			}
			assert.Equal(t, test.expectValue.State, value.State)
			assert.Equal(t, test.expectValue.Deleted, value.Deleted)
		})
	}

	cancel()
}

=== RUN   TestEtcdV3Client
--- PASS: TestEtcdV3Client (5.01s)
=== RUN   TestEtcdV3Client/test1
{"level":"warn","ts":"2025-02-21T16:27:41.989034+0800","logger":"etcd-client","caller":"v3/retry_interceptor.go:63","msg":"retrying of unary invoker failed","target":"etcd-endpoints://0x1400036a5a0/127.0.0.1:2379","attempt":0,"error":"rpc error: code = DeadlineExceeded desc = latest balancer error: last connection error: connection error: desc = \"transport: authentication handshake failed: EOF\""}
create from etcd failed, err:context deadline exceeded
    --- PASS: TestEtcdV3Client/test1 (5.00s)
PASS

2. If etcd is configured with cert, it can be accessed normally

Context

Your Environment

• Calico version
• Calico dataplane (iptables, windows etc.)
• Orchestrator version (e.g. kubernetes, mesos, rkt):
• Operating System and version:
• Link to your project (optional):