Check if existing Anchore scan is failed before pulling

The Anchore stage currently checks if a SHA has been scanned before scanning. If it has, it pulls the existing data. If that scan failed for some reason, it still "exists" and fails when the pipeline tries to pull that data. We need to put a check in to see if the analysis we are trying to pull is a "failed" scan. If it is, then we delete it and scan again.