**DEPENDS ON: [[graceful reboot] Add the pre_reboot_hook script execution, add the watchdog arm before the reboot](https://github.com/sonic-net/sonic-utilities/pull/3203)**
#### Why I did it
Add support for the `graceful reboot` instead of the `sysfs power cycle` to avoid filesystem corruption
### How I did it
Rename the `platform_reboot` script to the `pre_reboot_hook`.
Remove the sysfs power cycle function, from now on the Debian reboot (`/sbin/reboot`) will be executed instead of the sysfs power cycle.
#### How to verify it
1. Start watching logs by using `show log -f` and `journalctl -p debug -f`
2. Execute the `reboot` command from the switch CLI
3. Check in logs that all systemd services terminated
