init: reboot immediately if /data isn't mounted

All of the logic in reboot.cpp is meant to safely shutdown services,
safely unmount emulated RW file systems, then finally unmount the
remaining RW file systems, particularly /data.  If /data hasn't been
mounted, then none of this logic is required.

Running this logic caused a lock up when shutting down blueline from
early-init.  Vold, or potentially a related HAL, locked up during the
ShutdownVold() calls.  debuggerd separately locked up in the watchdog
thread.

Therefore, this change immediately reboots if /data is not mounted.
It also removes the lines to call into debuggerd.  debuggerd will not
run due to SELinux in any case, so it can only be used when hands-on
debugging a device.

Bug: 141082587
Test: shutdown with /data mounted continues as normal
Test: shutdown from early-init immediately shuts the device down
Change-Id: I79c72346b17c7dfe57e955d9739bcaf559badc14