[vision] fix: add timeout for LRO result and mark it as flaky

fixes GoogleCloudPlatform#3674

Author: Takashi Matsuo

vision/cloud-client/detect/vision_async_batch_annotate_images.py

@@ -46,7 +46,7 @@ def sample_async_batch_annotate_images(
     operation = client.async_batch_annotate_images(requests, output_config)
 
     print("Waiting for operation to complete...")
-    response = operation.result()
+    response = operation.result(90)
 
     # The output is written to GCS with the provided output_uri as prefix
     gcs_output_uri = response.output_config.gcs_destination.uri

vision/cloud-client/detect/vision_async_batch_annotate_images_test.py

@@ -49,6 +49,7 @@ def bucket(storage_client):
         blob.delete()
 
 
+@pytest.mark.flaky(max_runs=3, min_passes=1)
 def test_sample_asyn_batch_annotate_images(storage_client, bucket, capsys):
     input_image_uri = os.path.join(GCS_ROOT, "label/wakeupcat.jpg")