qt, test: Recognize dialog object by name

src/qt/sendcoinsdialog.cpp

@@ -406,6 +406,7 @@ void SendCoinsDialog::presentPSBT(PartiallySignedTransaction& psbtx)
     msgBox.setInformativeText(tr("The PSBT has been copied to the clipboard. You can also save it."));
     msgBox.setStandardButtons(QMessageBox::Save | QMessageBox::Discard);
     msgBox.setDefaultButton(QMessageBox::Discard);
+    msgBox.setObjectName("psbt_copied_message");
     switch (msgBox.exec()) {
     case QMessageBox::Save: {
         QString selectedFilter;