bench cache: bump keys for network-coverage split (fix 404)

[Flotapponnier]

Summary

• Bumps 3 unstable_cache keys because split network-coverage into asset-registry + dex-network benches #1390 changed the bench SET (split network-coverage into asset-registry-coverage + dex-network-coverage)
• Without this, getBenchmark returns undefined for the 2 new slugs and prod 404s them (sitemap smoke tripped the auto-rollback on split network-coverage into asset-registry + dex-network benches #1390)

Test plan

• pnpm typecheck OK
• After deploy: curl -sI /benchmarks/asset-registry-coverage → 200
• curl -sI /benchmarks/dex-network-coverage → 200
• /benchmarks/network-coverage still 301 → asset-registry-coverage