12684: Stop retrying 422 responses in PySDK

12684: Stop retrying 422 responses in PySDK

The original motivation for this was to retry when the API server was
having database connectivity problems. The feeling eight years later is
that things have changed enough that, on balance, this isn't worth
retrying anymore.

I don't think this will have any real impact on current Arvados
software. In the main branch as I write this,
`check_http_response_status` only gets called in five places. Three of
those are in the main `arvados` module for job and task utilities, which
presumably nobody is using anymore. The other two talk to Keep, which
only returns 422 for hash mismatches, where a retry will definitely
never succeed.

Arvados-DCO-1.1-Signed-off-by: Brett Smith <brett.smith@curii.com>