WIP - unify Prefix <-> IP Pool relationships

[ajtmccarty]

TODO:

• review and clean up migration and test
• manual testing

To consider: graphql schema update could be breaking for queries that were using the attributes on the old resource_pool: NestedPaginatedCoreIPAddressPool! relationship b/c the new NestedPaginatedCoreIPPool! schema is basically empty, so accessing those fields will require fragments

Why

Closes #7070

What changed

How to review

How to test

# Commands to validate

Impact & rollout

• Backward compatibility:
• Performance:
• Config/env changes:
• Deployment notes:

Checklist

• Tests added/updated
• Changelog entry added (uv run towncrier create ...)
• External docs updated (if user-facing or ops-facing change)
• Internal .md docs updated (internal knowledge and AI code tools knowledge)
• I have reviewed AI generated content

[codspeed-hq]

Merging this PR will not alter performance

✅ 12 untouched benchmarks

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_{Comparing ajtm-05012026-unify-pool-rels (e22432b) with stable (9ab7bfb)¹}

Footnotes

1. No successful run was found on stable (34251a9) during the generation of this report, so fb134fb was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩