Golangci-lint reports several linting errors

[anurag-rajawat]

Fix linting violations identified by golangci-lint, such as:

controllers/policy/network_policy.go:96:27: Error return value of `utils.ApplyOrUpdatePolicy` is not checked (errcheck)
        utils.ApplyOrUpdatePolicy(ctx, c, policy, policy.Name)
                                 ^
controllers/policy/network_policy.go:87:6: func `createCiliumNetworkPolicy` is unused (unused)
func createCiliumNetworkPolicy(ctx context.Context, intent *intentv1.SecurityIntent) *ciliumv2.CiliumNetworkPolicy {
     ^
controllers/policy/network_policy.go:91:6: func `createKubeArmorNetworkPolicy` is unused (unused)
func createKubeArmorNetworkPolicy(ctx context.Context, intent *intentv1.SecurityIntent) *kubearmorpolicyv1.KubeArmorPolicy {
     ^
controllers/policy/network_policy.go:95:6: func `applyCiliumNetworkPolicy` is unused (unused)
func applyCiliumNetworkPolicy(ctx context.Context, c client.Client, policy *ciliumv2.CiliumNetworkPolicy) {