Remove use CValidationInterface in wallet code

This commit does not change behavior.

src/wallet/test/wallet_test_fixture.cpp

@@ -13,12 +13,7 @@ WalletTestingSetup::WalletTestingSetup(const std::string& chainName):
 {
     bool fFirstRun;
     m_wallet.LoadWallet(fFirstRun);
-    RegisterValidationInterface(&m_wallet);
+    m_wallet.m_chain_notifications_handler = m_chain->handleNotifications(m_wallet);
 
     RegisterWalletRPCCommands(tableRPC);
 }
-
-WalletTestingSetup::~WalletTestingSetup()
-{
-    UnregisterValidationInterface(&m_wallet);
-}

src/wallet/test/wallet_test_fixture.h

@@ -17,7 +17,6 @@
  */
 struct WalletTestingSetup: public TestingSetup {
     explicit WalletTestingSetup(const std::string& chainName = CBaseChainParams::MAIN);
-    ~WalletTestingSetup();
 
     std::unique_ptr<interfaces::Chain> m_chain = interfaces::MakeChain();
     CWallet m_wallet;