Finalize conversion for FKs targeting p_ci_builds - 3 self-managed

What does this MR do and why?

Completes the FK swap for p_ci_builds_metadata and p_ci_runner_machine_builds for self-managed. These migrations were executed on .com with:

• !124310 (merged) skipped on CI database because of wraparound autovacuum on ci_builds
• !126122 (merged) - ReplaceOldFkPCiBuildsMetadataToBuildsV2 failed to get the exclusive lock on ci_builds
• !126701 (merged) - successfully executed ReplaceOldFkPCiBuildsMetadataToBuildsV2 instructions during the weekend.

They will be no-op on .com.

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.

Related to #414396 (closed)