Protect some L1 menu clients against missing l1menu
- in case no menu json file is available LVL1ConfigSvc did save uninitialized menu in DetectorStore. Now it will not save anything. That way clients can check on the handle validity, rather then the menu content
- Protected TrigSignatureMoniMT and TrigALFAROBMonitor against missing menu. Before it was simply aborting, which was not a good solution if we have no menu.
- Also fixed some random segfault of TrigSignatureMoniMT due to uninitialized values
Addresses ATR-20826