Mechanism to ensure local data sync thread is always running

[nitisht]

The local data sync thread is responsible for moving the data to a local directory and then move it to object storage as needed. If this thread crashes for any reason, we should be able detect that, try restarting the thread.

If the thread can't be respawned due to whatever reasons, the server should at the end of granularity period should stop taking post events (because we can't ensure data integrity).