[SDKs] one_task_per_input_stream fails due to unsupported APIs. Remove it from docs, examples, and SDK.
arvados.StreamReader(...).tokens()API disappeared, so it crashes (see 4696-streamreader-tokens branch for fix).
- It probably should be using
.tokens()anyway, since task input should be a manifest rather than an array of tokens.
get_task_param_task_mount(manifest_text)surely doesn't work (perhaps just document this for now -- reading the stream with the Python library should work).