chore(tests): add expected failure

Author: fabianrbz

tools/automated-tests/.env.test

@@ -48,3 +48,4 @@ TESTS_GITHUB_PAT='test'
 
 TESTS_CLOUDSMITH_TOKEN='test'
 
+TESTS_XAI_API_KEY='test'

tools/automated-tests/config/expected_failures.yaml

@@ -26,4 +26,5 @@ input/instructions/how-to/use-ai-gcp-model-armor-plugin/gateway.yaml: "Expected:
 input/instructions/how-to/compare-llm-models-accuracy/gateway.yaml: "Expected: request 1 to have status code 200, got: 401."
 input/instructions/how-to/use-agno-with-ai-proxy/gateway.yaml: "Expected: command to have return code 0, got: 1"
 input/instructions/how-to/use-langchain-with-ai-proxy/gateway.yaml: "Expected: command to have return code 0, got: 1"
-input/instructions/how-to/azure-batches/gateway.yaml: "Expected: request http://localhost:8000/files to have status code 201, got: 401."
+input/instructions/how-to/azure-batches/gateway.yaml: "Expected: request http://localhost:8000/files to have status code 201, got: 401."
+input/instructions/how-to/set-up-ai-proxy-for-image-generation-with-grok/gateway.yaml: "Expected: request http://localhost:8000/anything to have status code 201, got: 400."