Fix DISALLOW_SAFE_BOOT on HSUM

Check the restriction on the correct user.

Bug: 346329112
Test: 1. Install TestDPC on a HSUM device
      2. Set as DO: adb shell dpm set-device-owner --user 10 com.afwsamples.testdpc/.DeviceAdminReceiver
      3. Enable "Disallow safe boot" in TestDPC
      4  Trigger Power menu
      5. Long press "Power off" or "Restart" button
      6. Verify it doesn't show the dialog to reboot to safe mode
Flag: EXEMPT bugfix
Change-Id: I97f08cdf88b8f14673c1dd48b920102a02b18afd