Merge bitcoin#29055: tests, bench: Fix issue with CWallet::LoadWallet() being called in the wrong places

bd7f5d3 wallet: Assert that the wallet is not initialized in LoadWallet (Andrew Chow)
fb0b6ca tests, bench: Remove incorrect LoadWallet() calls (Andrew Chow)

Pull request description:

  `CWallet::LoadWallet()` expects to be called after a `CWallet` is constructed, but before any of its member functions called. Doing so invalidates pointers which causes issues with some PRs and branches that I am working on. This was being used incorrectly in a few tests and benchmarks, resulting in segfaults.

  As a precaution for this kind of issue in the future, I've also added a few asserts to `LoadWallet()` so that developers will notice when it is used incorrectly.

  As similar issue was fixed in bitcoin#27666

ACKs for top commit:
  S3RK:
    ACK bd7f5d3
  furszy:
    ACK bd7f5d3

Tree-SHA512: 7664f12b8452994e7fc4d7d4f77697fb5f75edb0dba95ba99a4a23ec03d5b8e0ecbdcb7635547a0e8b4f89f708f98dcb5d039df0559e24b1ae411ed630e16e14

Author: fanquake

src/bench/wallet_create_tx.cpp

@@ -16,7 +16,6 @@
 
 using wallet::CWallet;
 using wallet::CreateMockableWalletDatabase;
-using wallet::DBErrors;
 using wallet::WALLET_FLAG_DESCRIPTORS;
 
 struct TipBlock
@@ -90,7 +89,6 @@ static void WalletCreateTx(benchmark::Bench& bench, const OutputType output_type
         LOCK(wallet.cs_wallet);
         wallet.SetWalletFlag(WALLET_FLAG_DESCRIPTORS);
         wallet.SetupDescriptorScriptPubKeyMans();
-        if (wallet.LoadWallet() != DBErrors::LOAD_OK) assert(false);
     }
 
     // Generate destinations
@@ -146,7 +144,6 @@ static void AvailableCoins(benchmark::Bench& bench, const std::vector<OutputType
         LOCK(wallet.cs_wallet);
         wallet.SetWalletFlag(WALLET_FLAG_DESCRIPTORS);
         wallet.SetupDescriptorScriptPubKeyMans();
-        if (wallet.LoadWallet() != DBErrors::LOAD_OK) assert(false);
     }
 
     // Generate destinations

src/wallet/test/util.cpp

@@ -24,7 +24,6 @@ std::unique_ptr<CWallet> CreateSyncedWallet(interfaces::Chain& chain, CChain& cc
         LOCK2(wallet->cs_wallet, ::cs_main);
         wallet->SetLastBlockProcessed(cchain.Height(), cchain.Tip()->GetBlockHash());
     }
-    wallet->LoadWallet();
     {
         LOCK(wallet->cs_wallet);
         wallet->SetWalletFlag(WALLET_FLAG_DESCRIPTORS);

src/wallet/wallet.cpp

@@ -2292,6 +2292,8 @@ DBErrors CWallet::LoadWallet()
 {
     LOCK(cs_wallet);
 
+    Assert(m_spk_managers.empty());
+    Assert(m_wallet_flags == 0);
     DBErrors nLoadWalletRet = WalletBatch(GetDatabase()).LoadWallet(this);
     if (nLoadWalletRet == DBErrors::NEED_REWRITE)
     {