This minimal fix addresses offset persistence issues during consumer
group operations without introducing timeouts or delays.
KEY CHANGES:
1. OffsetFetch now checks SMQ storage as fallback when offset not found in memory
2. Immediately cache offsets in in-memory map after SMQ fetch
3. Prevents future SMQ lookups for same offset
4. No retry logic or delays that could cause timeouts
ROOT CAUSE:
When offsets are persisted to SMQ but not yet in memory cache,
consumers would get -1 (not found) and default to offset 0 or
auto.offset.reset, causing message loss.
FIX:
Simple fallback to SMQ + immediate cache ensures offset is always
available for subsequent queries without delays.
chrislu
5c0f215eb5