Stop translating command line options

Many options are extremely technical, and refer internals, making it
difficult to translate usefully. This came up in discussion of e.g.
 #10949. If a message is not understood by translators (which are
typically end-users, not developers) they'll either translate it
literally, making it harder to understand instead of easier, with the
added drawback of the user no longer being able to google it.

Also the translation was only working for bitcoin-qt as with
the console programs, there is no translation backend. So it was
injecting never-used translation messages for bitcoin-cli, -tx.

For these reasons, stop translating options help completely. This should
not affect the output **in any way** except for bitcoin-qt when a
non-English language is configured in the locale.

This implements #10962.

src/qt/utilitydialog.cpp

@@ -70,8 +70,8 @@ HelpMessageDialog::HelpMessageDialog(interfaces::Node& node, QWidget *parent, bo
         ui->helpMessage->setVisible(false);
     } else {
         setWindowTitle(tr("Command-line options"));
-        QString header = tr("Usage:") + "\n" +
-            "  bitcoin-qt [" + tr("command-line options") + "]                     " + "\n";
+        QString header = "Usage:\n"
+            "  bitcoin-qt [command-line options]                     \n";
         QTextCursor cursor(ui->helpMessage->document());
         cursor.insertText(version);
         cursor.insertBlock();