test(ci): skip e2e_multi_validator_node_key_store entirely on merge-train/spartan

.test_patterns.yml

@@ -379,13 +379,17 @@ tests:
     owners:
       - *spyros
 
-  # http://ci.aztec-labs.com/9a5fa90aa18f62e7
-  # Under proposer pipelining the multi-validator web3signer suite intermittently
-  # drops the first concurrently-submitted tx at the P2P layer before it reaches
-  # a proposer, failing waitForTx at Promise.all index 0 in the "should build
-  # blocks & attest with multiple validator keys" case.
+  # Multi-validator web3signer suite is unstable under proposer pipelining:
+  # two distinct failure modes have been seen in the same "should build blocks
+  # & attest with multiple validator keys" case — Promise.all index-0
+  # waitForTx aborting with "Tx dropped by P2P node"
+  # (ci.aztec-labs.com/9a5fa90aa18f62e7), and the proposer missing the slot's
+  # 5-attestation deadline ("AttestationTimeoutError" / "Block .* not found .*
+  # reorg") on PR #23344 run 26370196367 (ci.aztec-labs.com/b91d3218b5e88ae4).
+  # Error-regex flake matches still let ci3 retry-and-fail both attempts. Skip
+  # outright on merge-train/spartan until proposer pipelining stabilises.
   - regex: "yarn-project/end-to-end/scripts/run_test.sh web3signer src/composed/web3signer/e2e_multi_validator_node_key_store.test.ts"
-    error_regex: "Tx dropped by P2P node"
+    skip: true
     owners:
       - *palla