* Drop signal CClientUIInterface::LoadWallet
* gui: Fix duplicate wallet showing up
The slot BitcoinGUI::addWallet can be invoked twice for the same
WalletModel due to a concurrent wallet being loaded after the first `connect()`:
```cpp
connect(wallet_controller, &WalletController::walletAdded, this, &BitcoinGUI::addWallet);
connect(wallet_controller, &WalletController::walletRemoved, this, &BitcoinGUI::removeWallet);
for (WalletModel* wallet_model : m_wallet_controller->getOpenWallets()) {
addWallet(wallet_model);
```
This is a backport of Core PR16963
Because `WalletFrame::addWallet` already returns a bool, that part of the patch wasn't necessary.