Instead of making 3 GraphQL API calls per collection (~300 total for
100 collections), collect all repo and user references across all
collections upfront, deduplicate them, and batch the GraphQL queries.

This reduces API round-trips from ~300 to ~10-15 (depending on total
unique items), significantly improving test suite performance while
maintaining the same validation coverage.

The rescue block claimed to fall back to per-test caching, but those
cache calls were removed from the test. A silent catch here would let
every subsequent API call hit the network uncached, likely causing
rate-limit failures. Let errors propagate so tests fail fast with a
clear reason.