fix(txcommon): dedupe blockchain events within a batch

[EnriqueL8]

Proposed changes

When the blockchain connector delivers the same on-chain log twice within one batch, FireFly emits two blockchain_event_received events with the same reference, pointing at the same blockchain_events row.

InsertNewBlockchainEvents' insert-or-get fallback queries the events table to decide whether a duplicate blockchain_events row still needs a notification, but that query only sees events committed in previous batches — the FF events for earlier entries of the current batch are inserted later, in maybePersistBlockchainEvents. So the second entry falls through the "partial success" branch and both end up in inserted.

Symptom observed:

DEBUG connector: Detected event 000012345/000000/000000/B=0xbeef…/L=00000000-1111-2222-3333-444444444444
DEBUG connector: Detected event 000012345/000000/000000/B=0xbeef…/L=00000000-1111-2222-3333-444444444444
WARN  txcommon: Blockchain event insert-many optimization failed: FF00195: PK violation
DEBUG events:   Emitting blockchain_event_received reference=99999999-eeee-4fff-aaaa-deadbeef0000
DEBUG events:   Emitting blockchain_event_received reference=99999999-eeee-4fff-aaaa-deadbeef0000

Originally thought about adding a new set with IDs to be O(1) but batches are small so we can iterate over the array

Types of changes

• Bug fix
• New feature added
• Documentation Update

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
internal/txcommon/txcommon.go	100.00% <100.00%> (ø)

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