Add environment variable check to Sample08_UpdateAnalyzerTest.setup()

Sample08_UpdateAnalyzerTest has a custom setup() method that builds a client.
This method now calls skipIfRequiredEnvironmentVariablesNotSet() to skip the test
when credentials are not available, preventing NullPointerException.

Author: Changjian Wang

sdk/contentunderstanding/azure-ai-contentunderstanding/src/test/java/com/azure/ai/contentunderstanding/generated/Sample08_UpdateAnalyzerTest.java

@@ -42,6 +42,9 @@ public class Sample08_UpdateAnalyzerTest {
 
     @BeforeEach
     public void setup() {
+        // Skip test if required credentials are not available
+        ContentUnderstandingClientTestBase.skipIfRequiredEnvironmentVariablesNotSet();
+
         String endpoint = Configuration.getGlobalConfiguration().get("CONTENTUNDERSTANDING_ENDPOINT");
         String key = System.getenv("AZURE_CONTENT_UNDERSTANDING_KEY");