test: flag e2e_p2p_duplicate_proposal_slash as flake under pipelining

[AztecBot]

Summary

Add .test_patterns.yml entry to flag e2e_p2p/duplicate_proposal_slash > slashes validator who sends duplicate proposals as a flake. Hit on http://ci.aztec-labs.com/930ddc9ede87059f and dequeued PR #23344 from the merge queue.

This is the same race family as #23501 — under pipelining the slasher's offense recording loses to the test's wait timeout.

Investigation

Failure: TimeoutError: Timeout awaiting duplicate proposal offense at retryUntil (yarn-project/foundation/src/retry/index.ts:90) from duplicate_proposal_slash.test.ts. The test triggers a duplicate checkpoint proposal from validator-1, advances time, and polls the slasher for a DUPLICATE_PROPOSAL offense. The offense never appears within the wait window and the test exits with code: 1 after 226 s.

Surrounding log signal: the run shows committee attestation collection timing out one slot earlier (AttestationTimeoutError: Timeout collecting attestations for slot 14: 2/3) under pipelining, so the duplicate-proposal slot's gossip path is degraded around the same window the test is polling.

Why a specific entry? The blanket src/e2e_p2p/.*\.test\.ts pattern with flake_group_id: e2e-p2p-epoch-flakes already covers this file, but only up to the group threshold of 4. On this PR the threshold was already consumed by other p2p flakes (sentinel_status_slash.parallel was FLAKED in the same run), so this failure escalated to FAILED and dequeued the merge train. Adding a specific entry with error_regex lets this exact failure mode be tolerated independently of the group threshold, matching #23501's approach for attested_invalid_proposal.

Follow-up

Proper source fix is on the slasher / p2p side, parallel to the work in spl/fix-ha-full-equivocation-check: ensure the duplicate-proposal detector sees both gossip arrivals even when committee attestation collection for the same slot is stalling. This patch is the quick unblock.

Test plan

• Flake regex matches the observed TimeoutError: Timeout awaiting duplicate proposal offense from the failure
• CI continues to run e2e_p2p/duplicate_proposal_slash.test.ts; failures now alert palla on #aztec3-ci instead of failing the build

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Created by claudebox · group: slackbot