adbd: lessen security constraints when the device is unlocked

ALLOW_ADBD_ROOT ('adb root') and ALLOW_ADBD_NO_AUTH (ro.adb.secure = 0)
are false in user build. This prevents a non-A/B device from running
Treble VTS because it requires 'adb root'. Without ALLOW_ADBD_NO_AUTH,
adb still can work if ro.adb.secure = 1. However, allowing it to be 0
is better for test automation.

The image combination in VTS is:
  - system.img (userdebug): provided by Googlg
  - boot.img (user): provided by the OEM  <-- adbd is here
  - vendor.img (user): provided by the OEM

This change allows 'adb root' and 'ro.adb.secure = 0' when the device is
unlocked in user build. No changes for userdebug/eng builds.

Note that the device must be unlocked when running VTS. Otherwise,
verified boot will prevent it from booting the system.img provided by
Google (no verity metadata).

Bug: 63313955
Bug: 63381692
Test: use the above image combination, check 'adb root' and
      'ro.adb.secure = 0' can work

Change-Id: I109d96c950e54c4fb0ac0c98b989a20593681e52