chore: Lower default relay batch timeout

[Eric-Warehime]

Closes https://linear.app/cosmoslabs/issue/FOU-1341/lower-default-batch-timeouts

3 is an arbitrary time I picked so lmk if there are suggestions or if we want to go even lower.

[linear-code]

FOU-1341

[greptile-apps]

Greptile Summary

Lowers the default receive and acknowledgement batch timeout for routes without explicit overrides.

• Changes DefaultBatchTimeout from 10 seconds to 3 seconds.
• Leaves the separate one-minute timeout-operation batch default unchanged.

Confidence Score: 5/5

The PR appears safe to merge because the shorter default only changes the intended batching latency and transaction-frequency tradeoff.

Routes without overrides will flush receive and acknowledgement batches sooner, while batch sizing, explicit overrides, timeout-operation batching, and relay correctness behavior remain unchanged.

Important Files Changed

Filename	Overview
link/internal/relay/pipeline/opts.go	Reduces the default receive and acknowledgement batch flush interval without changing override behavior or timeout-operation batching.

_{Reviews (1): Last reviewed commit: "Lower default relay batch timeout" | Re-trigger Greptile}

[dhfang]

ibc/link/internal/relay/dispatch/dispatcher.go

Line 17 in c73d6e7

const DefaultPollInterval = 5 * time.Second

can we also reduce this to like 1s