Lower UnableToConstructChange.shortfall values for balanceTx gold…

…en tests.

The previous commit adjusted the dummy output used by function
`performSelectionEmpty` so that it uses a null-length `Address` value.

This null-length `Address` value is identical to the one we used before
we adjusted `computeMinimumCoinForUTxO` to require a valid `Address`.

However, we were also able to adjust `performSelectionEmpty` so that it
no longer needs to validate minimum ada quantities of user-specified
outputs, and consequently we were able to reduce the dummy output's
`Coin` value to just `Coin 1`, which has the smallest space cost of
any non-zero `Coin` value.

This results in a further reduction in cost overestimation while
constructing change, which results in smaller `shortfall` values within
`UnableToConstructChange` errors.

lib/shelley/test/data/balanceTx/delegate/golden

@@ -38,10 +38,10 @@
  1.850000,ErrBalanceTxSelectAssets (ErrSelectAssetsSelectionError (SelectionBalanceErrorOf (BalanceInsufficient (BalanceInsufficientError {utxoBalanceAvailable = TokenBundle {coin = Coin 1850000, tokens = TokenMap (fromList [])}, utxoBalanceRequired = TokenBundle {coin = Coin 2000000, tokens = TokenMap (fromList [])}}))))
  1.900000,ErrBalanceTxSelectAssets (ErrSelectAssetsSelectionError (SelectionBalanceErrorOf (BalanceInsufficient (BalanceInsufficientError {utxoBalanceAvailable = TokenBundle {coin = Coin 1900000, tokens = TokenMap (fromList [])}, utxoBalanceRequired = TokenBundle {coin = Coin 2000000, tokens = TokenMap (fromList [])}}))))
  1.950000,ErrBalanceTxSelectAssets (ErrSelectAssetsSelectionError (SelectionBalanceErrorOf (BalanceInsufficient (BalanceInsufficientError {utxoBalanceAvailable = TokenBundle {coin = Coin 1950000, tokens = TokenMap (fromList [])}, utxoBalanceRequired = TokenBundle {coin = Coin 2000000, tokens = TokenMap (fromList [])}}))))
- 2.000000,ErrBalanceTxSelectAssets (ErrSelectAssetsSelectionError (SelectionBalanceErrorOf (UnableToConstructChange (UnableToConstructChangeError {requiredCost = Coin 182177, shortfall = Coin 182177}))))
- 2.050000,ErrBalanceTxSelectAssets (ErrSelectAssetsSelectionError (SelectionBalanceErrorOf (UnableToConstructChange (UnableToConstructChangeError {requiredCost = Coin 182177, shortfall = Coin 132177}))))
- 2.100000,ErrBalanceTxSelectAssets (ErrSelectAssetsSelectionError (SelectionBalanceErrorOf (UnableToConstructChange (UnableToConstructChangeError {requiredCost = Coin 182177, shortfall = Coin 82177}))))
- 2.150000,ErrBalanceTxSelectAssets (ErrSelectAssetsSelectionError (SelectionBalanceErrorOf (UnableToConstructChange (UnableToConstructChangeError {requiredCost = Coin 182177, shortfall = Coin 32177}))))
+ 2.000000,ErrBalanceTxSelectAssets (ErrSelectAssetsSelectionError (SelectionBalanceErrorOf (UnableToConstructChange (UnableToConstructChangeError {requiredCost = Coin 180725, shortfall = Coin 180725}))))
+ 2.050000,ErrBalanceTxSelectAssets (ErrSelectAssetsSelectionError (SelectionBalanceErrorOf (UnableToConstructChange (UnableToConstructChangeError {requiredCost = Coin 180725, shortfall = Coin 130725}))))
+ 2.100000,ErrBalanceTxSelectAssets (ErrSelectAssetsSelectionError (SelectionBalanceErrorOf (UnableToConstructChange (UnableToConstructChangeError {requiredCost = Coin 180725, shortfall = Coin 80725}))))
+ 2.150000,ErrBalanceTxSelectAssets (ErrSelectAssetsSelectionError (SelectionBalanceErrorOf (UnableToConstructChange (UnableToConstructChangeError {requiredCost = Coin 180725, shortfall = Coin 30725}))))
  2.200000,0.200000,0.175401
  2.250000,0.250000,0.175401
  2.300000,0.300000,0.175401