Draft: PoC for the orphan job artifact final objects clean up rake task

This is for #423074 (closed)

This is only a PoC because:

• We don't have the specs yet
• We might want to split this into smaller MRs, like separate the Gemfile updates on its own.

But the code itself is already ready for review.

Tested this manually with GCP and Minio, both with bucket_prefix scenario.