Define NoOptDefVal for validate flag

validate flag does not have default value defined when there is no
parameter passed, therefore it tries to use next irrelevant flag.

This PR defines NoOptDefVal for validate flag which is set "strict".

test/cmd/create.sh

@@ -170,6 +170,12 @@ run_kubectl_create_validate_tests() {
 
   create_and_use_new_namespace
 
+   ## test --validate no value expects default strict is used
+   kube::log::status "Testing kubectl create --validate"
+   # create and verify
+   output_message=$(! kubectl create -f hack/testdata/invalid-deployment-unknown-and-duplicate-fields.yaml --validate 2>&1)
+   has_one_of_error_message "${output_message}" 'strict decoding error' 'error validating data'
+
   ## test --validate=true
   kube::log::status "Testing kubectl create --validate=true"
   # create and verify