Don't keep deposit script utxo in local state (#1692)

### Why

This is a leftover from off-chain changes needed to implement #199

We kept in the local state a map of UTxO we already observed so this
simplifies the code around that since the observed UTxO is already to be
found in the chain state UTxO. Now we keep a list of `[(TxId, UTxO)]`
where UTxO is just there to check off-chain if the next snapshot is
snapshotting exactly what we saw already as (`utxoToCommit`).

### What

Remove the local map and fields in the observations for
increment/recover and rely completely on observed UTxO (`spendableUTxO`)

---

<!-- Consider each and tick it off one way or the other -->
* [x] CHANGELOG updated or not needed
* [x] Documentation updated or not needed
* [x] Haddocks updated or not needed
* [x] No new TODOs introduced or explained herafter

CHANGELOG.md

@@ -15,7 +15,6 @@ changes.
      Important to note is that on-chain security is not implemented and hydra-node in this
      state is not releasable!
      Missing off-chain items to implement as a series of next PR's:
-      - Use the observed UTxO to construct increment/recover
       - Add documentation to explain the feature
       - Implement tests scenarios outlined in the [incremental-commit] (https://github.com/cardano-scaling/hydra/issues/199) issue
       - Remove Commit client input since it is unused

hydra-cardano-api/src/Cardano/Api/UTxO.hs

@@ -62,9 +62,13 @@ resolve k = Map.lookup k . toMap
 pairs :: UTxO' out -> [(TxIn, out)]
 pairs = Map.toList . toMap
 
--- | Find first 'UTxO' which satisfies given predicate.
+-- | Find first 'UTxO' using the output in predicate.
 find :: (out -> Bool) -> UTxO' out -> Maybe (TxIn, out)
-find fn utxo = List.find (fn . snd) $ pairs utxo
+find fn = findBy (fn . snd)
+
+-- | Find first 'UTxO' using both input and output in predicate.
+findBy :: ((TxIn, out) -> Bool) -> UTxO' out -> Maybe (TxIn, out)
+findBy fn utxo = List.find fn $ pairs utxo
 
 -- | Filter UTxO to only include 'out's satisfying given predicate.
 filter :: (out -> Bool) -> UTxO' out -> UTxO' out

hydra-cluster/src/Hydra/Cluster/Scenarios.hs

@@ -437,7 +437,7 @@ singlePartyCommitsScriptBlueprint tracer workDir node hydraScriptsTxId =
       waitFor hydraTracer 10 [n1] $
         output "CommitApproved" ["headId" .= headId, "utxoToCommit" .= scriptUTxO']
       waitFor hydraTracer 10 [n1] $
-        output "CommitFinalized" ["headId" .= headId, "utxo" .= scriptUTxO', "theDeposit" .= getTxId (getTxBody tx)]
+        output "CommitFinalized" ["headId" .= headId, "theDeposit" .= getTxId (getTxBody tx)]
 
       send n1 $ input "GetUTxO" []
 
@@ -731,7 +731,7 @@ canCommit tracer workDir node hydraScriptsTxId =
       waitFor hydraTracer 10 [n1] $
         output "CommitApproved" ["headId" .= headId, "utxoToCommit" .= commitUTxO]
       waitFor hydraTracer 10 [n1] $
-        output "CommitFinalized" ["headId" .= headId, "utxo" .= commitUTxO, "theDeposit" .= getTxId (getTxBody tx)]
+        output "CommitFinalized" ["headId" .= headId, "theDeposit" .= getTxId (getTxBody tx)]
 
       send n1 $ input "GetUTxO" []