Adjust message box text for sync removal

Since the context menu text was changed to "Remove Sync" it seems sensible to also change the title of this message box to match.
https://github.com/owncloud/client/issues/3745

src/gui/accountsettings.cpp

@@ -245,7 +245,7 @@ void AccountSettings::slotRemoveCurrentFolder()
         qDebug() << "Remove Folder alias " << alias;
         if( !alias.isEmpty() ) {
             QMessageBox messageBox(QMessageBox::Question,
-                                   tr("Confirm Folder Remove"),
+                                   tr("Confirm Sync Removal"),
                                    tr("<p>Do you really want to stop syncing the folder <i>%1</i>?</p>"
                                       "<p><b>Note:</b> This will <b>not</b> delete any files.</p>").arg(alias),
                                    QMessageBox::NoButton,