Test scripts: use larger disk io timeouts with endurance test to make it work with failure simulation and "slow" disks.
Chunk server: only pay attention to panic on invalid chunk if the file size is greater than 0, to eliminated false positives from abandoned files. Fix remote sync state machine authentication setting logic, and the corresponding parameter name. Report authentication (on/off) state of meta, client, and remote sync state machines in heartbeat in order facilitate debugging.
Chunk server: explicitly convert booleans to integers in chunk server heartbeat to ensure that the emitted values are always numbers.