Long-running code results in `requests` `ChunkedEncodingError` exception (broken connection)

I have a script ingesting ~200 GB of landsat imagery with the current multi-threaded implementation (no Dataflow). Eventually, I always get an exception like:

```
requests.exceptions.ChunkedEncodingError: ('Connection broken: IncompleteRead(9186238 bytes read, 1299762 more expected)', IncompleteRead(9
186238 bytes read, 1299762 more expected))
```

This occurs in the [`common.robust_getitem`](https://github.com/google/Xee/blob/f05e82b751d54433099c89c9ce7d68c629c592dc/xee/ext.py#L463) call.

I've had some success in reducing the frequency of this exception by lowering the chunk size, so e.g. I can make it to ~150 GB instead of failing after 90, although hard to say if that improvement is reliable since it is non-deterministic.

I am not sure of the root cause of this-- it could be due to a multithreading/lock issue, or the server is prematurely closing the connection. Either way, the current code only applies the retry/backoff logic to `EEException`s. I've had success by retrying on any `Exception` rather than just `EEException` but that is not an ideal solution.

I'd imagine that we don't see this in Dataflow because it has its own worker retry logic?