test(zebra-consensus): assert the Orchard proof failure, not a UTXO timeout

`block_with_garbage_orchard_proofs_is_rejected` discarded the UTXO map
from `mock_transparent_transfer` and sent an empty `known_utxos` for a
transaction with a transparent input. The mock state never answers the
lookup, so the request failed on `UTXO_LOOKUP_TIMEOUT` six minutes later
and `assert!(resp.is_err())` was satisfied by that timeout: the test
never reached proof verification, and would have passed with Orchard
proof checking removed. It was also the slowest test in the CI profile,
at 360s of the run's 623s.

Pass the funding UTXO through and assert `Halo2VerificationFailed`, so
the rejection under test is the one the CVE-2026-34377 advisory is about.
The test now finishes in 0.7s.

Author: upbqdn

zebra-consensus/src/transaction/tests.rs

@@ -4598,7 +4598,7 @@ async fn block_with_garbage_orchard_proofs_is_rejected() {
         .activation_height(&Network::Mainnet)
         .expect("Nu6 activation height is specified");
     let fund_height = (height - 1).expect("too small");
-    let (input, output, _known_utxos) = mock_transparent_transfer(
+    let (input, output, known_utxos) = mock_transparent_transfer(
         fund_height,
         true,
         0,
@@ -4620,19 +4620,31 @@ async fn block_with_garbage_orchard_proofs_is_rejected() {
     let garbage_tx = with_garbage_orchard_authorization(tx.clone());
     assert_eq!(tx.hash(), garbage_tx.hash());
 
-    // submit garbage version as block tx, must be rejected
+    // Submit the garbage version as a block tx, which must be rejected.
+    //
+    // The funding UTXO has to be in `known_utxos`: the mock state never answers a lookup, so
+    // without it the request fails on `UTXO_LOOKUP_TIMEOUT` six minutes later and never reaches
+    // proof verification, which would make this test pass without checking any proof.
     let resp = verifier
         .clone()
         .oneshot(BlockRequest {
             transaction_hash: tx_hash,
             transaction: Arc::new(garbage_tx),
-            known_utxos: Arc::new(HashMap::new()),
+            known_utxos: Arc::new(known_utxos),
             height,
             time: Utc::now(),
         })
         .await;
 
-    assert!(resp.is_err(), "garbage proof must be rejected");
+    // Buffer boxes the service error, so downcast to check the specific variant.
+    let err = resp.expect_err("garbage proof must be rejected");
+    let tx_err = err
+        .downcast::<TransactionError>()
+        .expect("error should downcast to TransactionError");
+    assert!(
+        matches!(*tx_err, TransactionError::Halo2VerificationFailed),
+        "expected Halo2VerificationFailed for garbage Orchard proofs; got: {tx_err:?}"
+    );
 }
 
 /// Regression test for the mempool-cache expiry bypass vulnerability.