scripted-diff: Rename ShowModalDialogAndDeleteOnClose

-BEGIN VERIFY SCRIPT-
sed -i 's/ShowModalDialogAndDeleteOnClose/ShowModalDialogAsynchronously/' -- $(git grep -l -e "ShowModalDialogAndDeleteOnClose")
-END VERIFY SCRIPT-

It is important to highlight that a modal dialog is showed
asynchronously as there are cases when the synchronous QDialog::exec()
is required.

src/qt/walletframe.cpp

@@ -226,7 +226,7 @@ void WalletFrame::gotoLoadPSBT(bool from_clipboard)
 
     auto dlg = new PSBTOperationsDialog(this, currentWalletModel(), clientModel);
     dlg->openWithPSBT(psbtx);
-    GUIUtil::ShowModalDialogAndDeleteOnClose(dlg);
+    GUIUtil::ShowModalDialogAsynchronously(dlg);
 }
 
 void WalletFrame::encryptWallet()