chore(fast-inbox): re-enable multi_proof from this point in the stack (A-1378)

Remove the transitional skip added at the per-block-bundle branch. multi_proof was
observed passing in CI at this content (2-CPU, 65s on 2026-07-19) and passes on
next/merge-train, so the constrained-CPU slowdown introduced earlier in the stack is
resolved by here. The skip stays protective over the intervening branches where we
have no passing observation; from this branch upward the test runs normally.

Author: spalladino

.test_patterns.yml

@@ -378,16 +378,6 @@ tests:
     owners:
       - *alex
 
-  # multi_proof runs three prover nodes; with fake proofs the orchestrator still does circuit witness
-  # generation, and the per-block-bundle change from this point makes constrained parity (in_hash) hashing
-  # heavier. Under CI's 2-CPU limit that extra witgen starves the sequencer's L1 publish past its tx timeout,
-  # so the test is transitionally slow here. It passes on adequate hardware, and a later stack change that
-  # turns the in_hash parity into an unconstrained hint restores the margin — this skip is removed there.
-  - regex: "yarn-project/end-to-end/scripts/run_test.sh simple src/single-node/proving/multi_proof.test.ts"
-    skip: true
-    owners:
-      - *palla
-
   - regex: "yarn-project/end-to-end/scripts/run_test.sh compose src/composed/docs_examples.test.ts"
     error_regex: "maxFeesPerGas.feePerL2Gas must be greater than or equal to gasFees.feePerL2Gas,"
     owners: