Backfill pipeline execution policy enforced scans

Why are we doing this work

This is a follow-up issue for Account for configured Pipeline Execution Polic... (#498624 - closed). We've released it while documenting that it doesn't work for policies created before %17.10 due to missing metadata.

Backfill pipeline execution policy config links (!181151 - merged) was backfilled in %17.10 and can be finalized in %18.0. After that, we can depend on this data and backfill pipeline execution policy enforced_scans to fix inconsistencies with policies created before %17.10.

The merge request is ready: Backfill pipeline execution policy enforced scans (!181995 - merged).

Relevant links

Non-functional requirements

• Documentation:
• Feature flag:
• Performance:
• Testing:

Implementation plan

Verification steps