fix(ingestion): reduce MaxKeys to avoid uncatchable payload limit failure

[iankhou]

Mostly used AI. This is a config change.

Summary

• Reduces the starting MaxKeys for the reprocessing workflow's S3 ListObjectsV2 call from 1000 to 750
• Provides ~25% headroom below the 256KB Step Functions payload limit to prevent an uncatchable edge case

Problem

The reprocessing workflow has a retry mechanism that catches States.DataLimitExceeded and retries with fewer keys. However, there's an edge case where S3 returns a response just under 256KB — the state reports success, but Step Functions aborts the entire execution at the state transition boundary when internal metadata pushes the total payload over the limit. This ExecutionFailed event is not tied to a specific state, so addCatch never fires.

This was observed on 12/10 where Try1000 reported success but the execution was immediately aborted by Step Functions.

Fix

Reduce startMaxKeysValue from 1000 to 750 and minMaxKeysValue from 100 to 150. This is a temporary mitigation — a follow-up PR will make a longer term fix.

Test plan

• Verify snapshot tests pass (will need projen build to regenerate)
• Deploy and observe the next daily reprocessing run succeeds

[iankhou]

It worked!