graph, store: Use ctid-based join delete for call cache eviction

Replace the two-loop structure (fetch stale contracts, then delete
their call_cache rows in tiny batches) with a single adaptive loop
that joins call_cache to call_meta directly and deletes by ctid.

The old approach did `WHERE contract_address = ANY(N addresses)` on
the 6.9B row call_cache table repeatedly, which required expensive
index scans. The new approach lets Postgres join the small filtered
call_meta result against call_cache using the contract_address index,
then deletes by physical row address (ctid), which is the fastest
possible delete path.

Also removes the GRAPH_STORE_STALE_CALL_CACHE_CONTRACTS_BATCH_SIZE
env var since batch size is now fully controlled by AdaptiveBatchSize.