DeviceStateMonitor and unit test polish

DeviceStateMonitorTest has @FlakyTest cases which get undetermistic
result when test in different context.

This CL remove those flakiness by
- Initializing all states to off to have a determistic starting point.
- Reseting mSimulatedCommandsVerifier to eliminate the accumuated
  impact of Mockito.verify() on the follow test cases.

This CL also
- Add missing debug info of log and dumpstate for DeviceStateMonitor.
- Add more test cases to cover more methods.
- Clear up unused fields and comments for DeviceStateMonitor.
- Remove hard-codes with constants in DeviceStateMonitorTest.
- Pass all test cases in both Cuttlefish and Pixel3 phone.

Bug: 149223121
Test: atest DeviceStateMonitorTest
Change-Id: I987407ef812c83b10b84ba59c1f4010a0d27c143