* correct the wait and timeout mechanism for better CPU usage.
* Models: AS7726-32X, AS5835-54X

Signed-off-by: Sean Wu <sean_wu@edge-core.com>

* The original design will use 'docker' to check operating environment.
  But that command might get stuck occasionally when it is called in the
  context of 'determine-reboot-cause.service'. It is suspetced the
  reason why it gets stucked is related to the service status of
  'containerd'.
* Change to use 'which systemctl' to check operation environment.
  When systemctl exists, returns 0. (In Host os env)
  When it does not exist, returns 1. (In docker os env)

Signed-off-by: Sean Wu <sean_wu@edge-core.com>