Debugger: Keep auto setting for debugger language when widget is shown

Do not hard code the debugger languages when the widget is shown the first
time (through the toggle() signal). React to the clicked() signal instead.

Change-Id: I1ee29a30d23eb9c7faead92c50552c1abf9c7792
Reviewed-by: hjk <hjk121@nokiamail.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Aurindam Jana <aurindam.jana@digia.com>