Edge worker maintenance state is remembered if worker crashes

[majorosdonat]

If the worker is in maintenance mode, and crashes, or shut down NOT gracefully, then the state will remain in MAINTENANCE_MODE and later will be set to UNKNOWN by the executor. So in the end it will not be in OFFLINE_MAINTENANCE, which means, that during startup it will start normally instead of maintenance.
So 2 loigcs were modified to prevent this:

1. The executor will not set to unknown if the dead worker's last state is maintenance, but to OFFLINE_MAINTENANCE.
2. If the worker wants to register the STARTING state, but the previous state was maintenance or offline maintenance, then the state will remain maintenance

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[jscheffl]

Thanks for the fix! Looks good!