AnkiHubRequestError: AnkiHub request error: 503 Slow Down

[sentry-io]

Sentry Issue: ANKIHUB_ADDON-2A0

AnkiHubRequestError: AnkiHub request error: 503 Slow Down
(9 additional frame(s) were not displayed)
...
  File "concurrent.futures._base", line 438, in result
  File "concurrent.futures._base", line 390, in __get_result
  File "concurrent.futures.thread", line 52, in run
  File "1322529746/ankihub_client/ankihub_client.py", line 377, in _zip_and_upload_assets_chunk
    self._upload_file_to_s3_with_reusable_presigned_url(
  File "1322529746/ankihub_client/ankihub_client.py", line 404, in _upload_file_to_s3_with_reusable_presigned_url
    raise AnkiHubRequestError(s3_response)

[RisingOrange]

From what I saw on Sentry this error can happen in theses situations:

• when uploading images - this is done in multiple threads and apparently it's sometimes too fast and S3 responds with HTTP 503
• when multiple errors happen short after another in Anki (they might be caused by our add-on, but our add-on is also reporting errors that weren't caused by it to Sentry), the event is sent to sentry each time and Sentry responds with HTTP 503

#569 should help with the first type of situation, because it makes it so that S3 requests are retried on failure.