wallet: Replace CWalletTx in COutput with COutPoint and CTxOut

Instead of having a pointer to the CWalletTx in COutput, we can just
store the COutPoint and the CTxOut as those are the only things we need
from the CWalletTx. Other things CWalletTx used to provide were time and
fIsFromMe but these are also being stored by COutput.

src/wallet/test/coinselector_tests.cpp

@@ -331,7 +331,7 @@ BOOST_AUTO_TEST_CASE(bnb_search_test)
         add_coin(coins, *wallet, 2 * CENT, 6 * 24, false, 0, true);
         CCoinControl coin_control;
         coin_control.fAllowOtherInputs = true;
-        coin_control.Select(COutPoint(coins.at(0).tx->GetHash(), coins.at(0).i));
+        coin_control.Select(coins.at(0).outpoint);
         coin_selection_params_bnb.m_effective_feerate = CFeeRate(0);
         const auto result10 = SelectCoins(*wallet, coins, 10 * CENT, coin_control, coin_selection_params_bnb);
         BOOST_CHECK(result10);

src/wallet/test/wallet_tests.cpp

@@ -588,7 +588,7 @@ BOOST_FIXTURE_TEST_CASE(ListCoinsTest, ListCoinsTestingSetup)
     for (const auto& group : list) {
         for (const auto& coin : group.second) {
             LOCK(wallet->cs_wallet);
-            wallet->LockCoin(COutPoint(coin.tx->GetHash(), coin.i));
+            wallet->LockCoin(coin.outpoint);
         }
     }
     {