bench: Use DescriptorScriptPubKeyMan for wallet things

For wallet related benchmarks that need a ScriptPubKeyMan for operation,
use a DescriptorScriptPubKeyMan

src/bench/coin_selection.cpp

@@ -33,7 +33,6 @@ static void CoinSelection(benchmark::Bench& bench)
     NodeContext node;
     auto chain = interfaces::MakeChain(node);
     CWallet wallet(chain.get(), "", CreateDummyWalletDatabase());
-    wallet.SetupLegacyScriptPubKeyMan();
     std::vector<std::unique_ptr<CWalletTx>> wtxs;
     LOCK(wallet.cs_wallet);