Review feedback: add test case

ee/spec/frontend/vulnerabilities/vulnerability_training_spec.js

@@ -166,6 +166,7 @@ describe('VulnerabilityTraining component', () => {
         identifier                                      | exists
         ${SUPPORTED_IDENTIFIER_TYPES.cwe.toUpperCase()} | ${false}
         ${SUPPORTED_IDENTIFIER_TYPES.cwe.toLowerCase()} | ${false}
+        ${'non-supported-identifier'}                   | ${true}
       `('sets it to "$exists" for "$identifier"', async ({ identifier, exists }) => {
         createApolloProvider();
         createComponent({ identifiers: [{ externalType: identifier, externalId: 'cwe-1' }] });