Wallet interface: do not load not used cold staking balances.

 None of the cold staking balances are being used from this helper class at the moment, the CS screen has its own model and is calculating the values on-demand. Guarding them behind a flag to be activated in the future if they are needed.

src/interfaces/wallet.cpp

@@ -19,8 +19,10 @@ namespace interfaces {
             result.unconfirmed_watch_only_balance = m_wallet.GetUnconfirmedWatchOnlyBalance();
             result.immature_watch_only_balance = m_wallet.GetImmatureWatchOnlyBalance();
         }
-        result.delegate_balance = m_wallet.GetDelegatedBalance();
-        result.coldstaked_balance = m_wallet.GetColdStakingBalance();
+        if (result.have_coldstaking) { // At the moment, the GUI is not using these two balances.
+            result.delegate_balance = m_wallet.GetDelegatedBalance();
+            result.coldstaked_balance = m_wallet.GetColdStakingBalance();
+        }
         result.shielded_balance = m_wallet.GetAvailableShieldedBalance();
         result.unconfirmed_shielded_balance = m_wallet.GetUnconfirmedShieldedBalance();
         return result;

src/interfaces/wallet.h

@@ -21,6 +21,7 @@ struct WalletBalances
     CAmount watch_only_balance{0};
     CAmount unconfirmed_watch_only_balance{0};
     CAmount immature_watch_only_balance{0};
+    bool have_coldstaking{false};
     CAmount delegate_balance{0};
     CAmount coldstaked_balance{0};
     CAmount shielded_balance{0};