Merge bitcoin/bitcoin#27780: fuzz: Avoid timeout in utxo_total_supply

fafb4da fuzz: Avoid timeout in utxo_total_supply (MarcoFalke)

Pull request description:

  Looks like for high block counts it may be better to mock the chain, otherwise a high limit will lead to fuzz input bloat and timeouts, see bitcoin/bitcoin#17860 (comment).

  It can be checked that the fuzz target can still find the CVE, see bitcoin/bitcoin#17860 (review) with a diff of:

  ```diff
  diff --git a/src/consensus/tx_check.cpp b/src/consensus/tx_check.cpp
  index f949655..6f4cfb5f51 100644
  --- a/src/consensus/tx_check.cpp
  +++ b/src/consensus/tx_check.cpp
  @@ -39,8 +39,6 @@ bool CheckTransaction(const CTransaction& tx, TxValidationState& state)
       // the underlying coins database.
       std::set<COutPoint> vInOutPoints;
       for (const auto& txin : tx.vin) {
  -        if (!vInOutPoints.insert(txin.prevout).second)
  -            return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-inputs-duplicate");
       }

       if (tx.IsCoinBase())
  ```

  Also, fix a nit, see bitcoin/bitcoin#17860 (comment)

ACKs for top commit:
  dergoegge:
    ACK fafb4da

Tree-SHA512: a28fe9cd6ebb4c9bed5a5b35be76c1c436a87586c8fc3b3c4c8559a4a77ac08098324370da421d794c99579882c0872b6b29415de47ade6a05a08504a3d494c4

Author: fanquake

src/test/fuzz/utxo_total_supply.cpp

@@ -119,7 +119,9 @@ FUZZ_TARGET(utxo_total_supply)
     current_block = PrepareNextBlock();
     StoreLastTxo();
 
-    LIMITED_WHILE(fuzzed_data_provider.remaining_bytes(), 100'000)
+    // Limit to avoid timeout, but enough to cover duplicate_coinbase_height
+    // and CVE-2018-17144.
+    LIMITED_WHILE(fuzzed_data_provider.remaining_bytes(), 2'000)
     {
         CallOneOf(
             fuzzed_data_provider,
@@ -142,14 +144,14 @@ FUZZ_TARGET(utxo_total_supply)
                 node::RegenerateCommitments(*current_block, chainman);
                 const bool was_valid = !MineBlock(node, current_block).IsNull();
 
+                if (duplicate_coinbase_height == ActiveHeight()) {
+                    // we mined the duplicate coinbase
+                    assert(current_block->vtx.at(0)->vin.at(0).scriptSig == duplicate_coinbase_script);
+                }
+
                 const auto prev_utxo_stats = utxo_stats;
                 if (was_valid) {
                     circulation += GetBlockSubsidy(ActiveHeight(), Params().GetConsensus());
-
-                    if (duplicate_coinbase_height == ActiveHeight()) {
-                        // we mined the duplicate coinbase
-                        assert(current_block->vtx.at(0)->vin.at(0).scriptSig == duplicate_coinbase_script);
-                    }
                 }
 
                 UpdateUtxoStats();