ppai/image-classification: add exponential retries to download file

[davidcavazos]

Description

Fixes #6463

Even though the Connection reset by peer is a transient error and we can't do much to solve it on our side, we retry the request with exponential backoff and hopefully it'll work at some point. This will hopefully decrease the number of flaky test runs.

Checklist

• I have followed Sample Guidelines from AUTHORING_GUIDE.MD
• README is updated to include all relevant information
• Tests pass: nox -s py-3.6 (see Test Environment Setup)
• Lint pass: nox -s lint (see Test Environment Setup)
• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• Please merge this PR for me once it is approved.
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample

[dandhlee]

3.8 Failed with this error:

Traceback (most recent call last):
  File "/workspace/people-and-planet-ai/image-classification/e2e_test.py", line 111, in model_endpoint_id
    deployed_model_id = deploy_model.deploy_model(
  File "/workspace/people-and-planet-ai/image-classification/deploy_model.py", line 80, in deploy_model
    deployed_model = response.result()
  File "/workspace/people-and-planet-ai/image-classification/.nox/py-3-8/lib/python3.8/site-packages/google/api_core/future/polling.py", line 135, in result
    raise self._exception
google.api_core.exceptions.ResourceExhausted: 429 The following quotas are exceeded: AutoMLImageClassificationDeployedModelNodes