Merge bitcoin-core/gui#609: wallet, refactor: Drop unused WalletModel::PaymentRequestExpired

151009cf76 qt, wallet, refactor: Drop unused `WalletModel::PaymentRequestExpired` (Hennadii Stepanov)

Pull request description:

  The `PaymentRequestExpired` value in the `WalletModel::StatusCode` enumeration has been unused since bitcoin/bitcoin#17165.

ACKs for top commit:
  furszy:
    ACK 151009cf, no usage for it.
  kristapsk:
    cr ACK 151009cf76, checked that `PaymentRequestExpired` is not referenced anywhere else.

Tree-SHA512: c2ea3443af5d369ca294d79559869f688aaa806b91ffe0090f3b34638a8377ec2f11d6f5c09cc2d11ab55035850237e60e992acba671097a6642c6bb9e709273

src/qt/sendcoinsdialog.cpp

@@ -757,10 +757,6 @@ void SendCoinsDialog::processSendCoinsReturn(const WalletModel::SendCoinsReturn
     case WalletModel::AbsurdFee:
         msgParams.first = tr("A fee higher than %1 is considered an absurdly high fee.").arg(BitcoinUnits::formatWithUnit(model->getOptionsModel()->getDisplayUnit(), model->wallet().getDefaultMaxTxFee()));
         break;
-    case WalletModel::PaymentRequestExpired:
-        msgParams.first = tr("Payment request expired.");
-        msgParams.second = CClientUIInterface::MSG_ERROR;
-        break;
     // included to prevent a compiler warning.
     case WalletModel::OK:
     default:

src/qt/walletmodel.h

@@ -66,8 +66,7 @@ public:
         AmountWithFeeExceedsBalance,
         DuplicateAddress,
         TransactionCreationFailed, // Error returned when wallet is still locked
-        AbsurdFee,
-        PaymentRequestExpired
+        AbsurdFee
     };
 
     enum EncryptionStatus