Fix flaky MultiAssetReturnCollateral test

Use retryUntilJustM to poll for the multi-asset UTxO instead of
waiting a fixed 1 block and querying once. The mint transaction may
not be confirmed within a single block, causing
findLargestMultiAssetUtxoWithAddress to return Nothing.

This matches the retry pattern already used for the script address
UTxO lookup a few lines below.

Author: Jimbo4350

cardano-testnet/test/cardano-testnet-test/Cardano/Testnet/Test/Cli/Plutus/MultiAssetReturnCollateral.hs

@@ -145,13 +145,9 @@ hprop_collateral_with_tokens = integrationWorkspace "collateral-with-tokens" $ \
   -- STEP 2: Attempt to spend from script with collateral containing tokens
   -- This will fail because collateral cannot contain non-ADA tokens
 
-  -- Wait for transactions to be processed and find UTxOs
-  _ <- waitForBlocks epochStateView 1
-  
-  -- Find the UTxO with tokens at wallet1 (for collateral)
-  txinCollateralWithTokensM <- 
+  -- Find the UTxO with tokens at wallet2 (for collateral)
+  (txinCollateralWithTokens, collateralTxOut) <- retryUntilJustM epochStateView (WaitForBlocks 10) $
     findLargestMultiAssetUtxoWithAddress epochStateView sbe $ T.pack maCollateralAddress
-  (txinCollateralWithTokens, collateralTxOut) <- H.evalMaybe txinCollateralWithTokensM
   H.note_ "Collateral TxOut"
   H.noteShow_  collateralTxOut
   -- Find the UTxO at the script address