NSFS | NC | Fail nsfs.js completely on system.json failure

[romayalon]

Explain the changes

1. Currently on nsfs.js system.json update issues we fail silently and keep running the endpoint even if got an error, we need to fail the whole NSFS service in this case.

Issues: Fixed #xxx / Gap #xxx

1. Fixed Noobaa is not starting the service by reading the configuration stored in the mount system post the system reboot.  #7857
2. we might need to think about more cases this could happen.

Testing Instructions:

1. start nsfs service before the config dir mounting is available.
2. (This can also easily be mocked by throwing an error from init_nsfs_system() try scope).

• Doc added/updated
• Tests added

[tangledbytes]

Yeah this makes sense. I think when I first added this, I deemed this failure to be non-critical (don't think it was valid assumption even then though).