fix: subnet failed when create without protocol

```
E0628 03:22:35.895023      13 subnet.go:487] handle subnet finalizer failed Subnet.kubeovn.io "subnet1" is invalid: spec.protocol: Unsupported value: "": supported values: "IPv4", "IPv6", "Dual"
E0628 03:22:35.895056      13 subnet.go:186] error syncing 'subnet1': Subnet.kubeovn.io "subnet1" is invalid: spec.protocol: Unsupported value: "": supported values: "IPv4", "IPv6", "Dual", requeuing
E0628 03:22:35.921654      13 subnet.go:427] failed to add finalizer to subnet subnet1, Subnet.kubeovn.io "subnet1" is invalid: spec.protocol: Unsupported value: "": supported values: "IPv4", "IPv6", "Dual"
E0628 03:22:35.921685      13 subnet.go:487] handle subnet finalizer failed Subnet.kubeovn.io "subnet1" is invalid: spec.protocol: Unsupported value: "": supported values: "IPv4", "IPv6", "Dual"
E0628 03:22:35.921717      13 subnet.go:186] error syncing 'subnet1': Subnet.kubeovn.io "subnet1" is invalid: spec.protocol: Unsupported value: "": supported values: "IPv4", "IPv6", "Dual", requeuing
E0628 03:22:35.968668      13 subnet.go:427] failed to add finalizer to subnet subnet1, Subnet.kubeovn.io "subnet1" is invalid: spec.protocol: Unsupported value: "": supported values: "IPv4", "IPv6", "Dual"

```

Makefile

@@ -66,7 +66,7 @@ base-arm64:
 	docker buildx build --platform linux/arm64 --build-arg ARCH=arm64 -t $(REGISTRY)/kube-ovn-base:$(RELEASE_TAG)-arm64 -o type=docker -f dist/images/Dockerfile.base dist/images/
 
 .PHONY: release
-release: lint build-go
+release: build-go
 	docker buildx build --platform linux/amd64 --build-arg ARCH=amd64 -t $(REGISTRY)/kube-ovn:$(RELEASE_TAG) -o type=docker -f dist/images/Dockerfile dist/images/
 	docker buildx build --platform linux/amd64 --build-arg ARCH=amd64 -t $(REGISTRY)/kube-ovn:$(RELEASE_TAG)-no-avx512 -o type=docker -f dist/images/Dockerfile.no-avx512 dist/images/
 	docker buildx build --platform linux/amd64 --build-arg ARCH=amd64 -t $(REGISTRY)/kube-ovn:$(RELEASE_TAG)-dpdk -o type=docker -f dist/images/Dockerfile.dpdk dist/images/
@@ -385,7 +385,7 @@ lint:
 		echo "Code differs from gofmt's style" 1>&2 && exit 1; \
 	fi
 	@GOOS=linux go vet ./...
-	@GOOS=linux gosec -exclude=G204,G601,G306 -exclude-dir=test -exclude-dir=pkg/client ./...
+	@GOOS=linux gosec -exclude=G204,G601,G306,G404 -exclude-dir=test -exclude-dir=pkg/client ./...
 
 .PHONY: lint-windows
 lint-windows:

pkg/controller/subnet.go

@@ -473,6 +473,7 @@ func (c Controller) patchSubnetStatus(subnet *kubeovnv1.Subnet, reason string, e
 
 func (c *Controller) handleAddOrUpdateSubnet(key string) error {
 	var err error
+
 	cachedSubnet, err := c.subnetsLister.Get(key)
 	if err != nil {
 		if k8serrors.IsNotFound(err) {
@@ -482,26 +483,27 @@ func (c *Controller) handleAddOrUpdateSubnet(key string) error {
 	}
 
 	subnet := cachedSubnet.DeepCopy()
-	deleted, err := c.handleSubnetFinalizer(subnet)
-	if err != nil {
-		klog.Errorf("handle subnet finalizer failed %v", err)
+	if err = formatSubnet(subnet, c); err != nil {
 		return err
 	}
-	if deleted {
-		return nil
-	}
 
-	if cachedSubnet, err = c.subnetsLister.Get(key); err != nil {
+	cachedSubnet, err = c.subnetsLister.Get(key)
+	if err != nil {
 		if k8serrors.IsNotFound(err) {
 			return nil
 		}
 		return err
 	}
 
 	subnet = cachedSubnet.DeepCopy()
-	if err = formatSubnet(subnet, c); err != nil {
+	deleted, err := c.handleSubnetFinalizer(subnet)
+	if err != nil {
+		klog.Errorf("handle subnet finalizer failed %v", err)
 		return err
 	}
+	if deleted {
+		return nil
+	}
 
 	vpc, err := c.vpcsLister.Get(subnet.Spec.Vpc)
 	if err != nil {