Consider all docker image pull errors as a script failure rather than a system failure

Overview

In !2995 (merged) we stoped considering docker pull failures, however we only do this for certain type of errors we should return a Build failure for all errors from pull.

For example, we still see the following failures in production:

Job failed (system failure): failed to pull image "xxxxxxxx:ff3e18f6" with specified policies [always]: Error response from daemon: Get https://xxxx.xxxxx.amazonaws.com/v2/sidekiqs/manifests/ff3e18f6: no basic auth credentials (manager.go:205:0s)