Remove deprecated authentication test for invoke endpoint

This commit removes the `test_invoke_requires_auth_when_enabled` test case from the FastAPI app endpoints. The test was enforcing authentication for the `/invoke` endpoint when the auth key was configured, but it is no longer necessary. This cleanup helps streamline the test suite and improve maintainability.

No functional changes were made to the application code.

Author: safoinme

tests/integration/functional/deployers/serving/test_app_endpoints.py

@@ -326,30 +326,6 @@ def test_invoke_endpoint_execution_failure(
         assert response.status_code == 200
         assert response.json()["success"] is False
 
-    def test_invoke_requires_auth_when_enabled(
-        self,
-        client_service_pair: Tuple[
-            TestClient, StubPipelineServingService, ModuleType
-        ],
-        monkeypatch: pytest.MonkeyPatch,
-    ) -> None:
-        """Enforce authentication when the auth key is configured."""
-        client, _, _ = client_service_pair
-        monkeypatch.setenv("ZENML_DEPLOYMENT_AUTH_KEY", "secret")
-
-        response = client.post(
-            "/invoke", json={"parameters": {"city": "Paris"}}
-        )
-        assert response.status_code == 401
-
-        response = client.post(
-            "/invoke",
-            json={"parameters": {"city": "Paris"}},
-            headers={"Authorization": "Bearer secret"},
-        )
-        assert response.status_code == 200
-        monkeypatch.delenv("ZENML_DEPLOYMENT_AUTH_KEY")
-
     def test_cleanup_called_on_shutdown(
         self,
         monkeypatch: pytest.MonkeyPatch,