scrubber: enable --exit-code and route alerts

[skyzh]

Currently the scrubber only exits with an error code if the scrubber suffers fatal errors itself. If something goes wrong with the tenant, it doesn't currently affect the exit code of the scrubber until we provide --exit-code in the parameter.

We will need to identify current fatal errors in prod, fix them or put them into warnings, and then add this parameter to the scrubber. That way, we can receive alerts in Slack if something goes wrong with the user.

• resolve staging error
• resolve prod error
• enable exit code -> alert