test(e2e): require cross-observer agreement on sentinel fault slot

[AztecBot]

Why

PR #23344 (merge-train/spartan) was dequeued because e2e_p2p/sentinel_status_slash.parallel.test.ts "slashes the proposer with INACTIVITY when checkpoint validation records invalid" flaked in shard ci/x3-full (run, log).

From the failing log:

• 14:36:28 malicious validator-1 broadcasts INVALID checkpoint for slot 11
• 14:37:24 only validator-2 records checkpoint-invalid at slot 11
• 14:38:29–31 when the malicious node is selected again at slot 27, validators 2/3/4/5/6 all record checkpoint-invalid at slot 27
• Test then failed with TimeoutError: Timeout awaiting sentinel status for 0x90f7…906 at slot 11

findObservedStatusSlot was polling only honestObservers[0] (validator-2), which had picked up the malicious proposer's gossip earlier than the other observers. It returned slot 11. assertAllObserversSentinelStatus then timed out polling the rest of the observers for a slot they had never recorded — they only recorded checkpoint-invalid at the next occurrence (slot 27).

What

Change findObservedStatusSlot to require cross-observer agreement: it now takes the full observerNodes list and returns the earliest slot where every honest observer has recorded expectedStatus. That guarantees the downstream assertAllObserversSentinelStatus call has a slot every observer can satisfy.

Times out — and fails — if no common fault slot is ever recorded, so a genuine detection failure is still caught.

Both flake-prone tests (checkpoint-unvalidated and checkpoint-invalid) use the same helper and benefit equally.

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Created by claudebox · group: slackbot

[AztecBot]

Flakey Tests

🤖 says: This CI run detected 1 tests that failed, but were tolerated due to a .test_patterns.yml entry.

\033FLAKED\033 (8;;http://ci.aztec-labs.com/53f70755104db82b�53f70755104db82b8;;�):  yarn-project/end-to-end/scripts/run_test.sh simple src/e2e_cross_chain_messaging/l1_to_l2.parallel.test.ts "can send an L1 to L2 message from a non-registered portal address consumed from private repeatedly" (395s) (code: 0)