Check RescueParty before using SysUI reboot message

RescueParty does not factory reset the device, but
the reboot message shown during reboot is misleading.
The logic is currently handled correctly outside of
SysUI, but the RescueParty case is not considered
when showSysuiReboot() is called. Instead, check
whether RescueParty has triggered this reboot before
calling into SysUI.

Test: Manual. Trigger rescue party after boot,
      ensure reboot message says "Power off" rather
      than "Factory data reset"
Bug: 197065751
Change-Id: Ibd2e776130f9c2cb437ec5515ea64e5d69a31bb8