Fix #29073394: Need to bind to scorer after user is unlocked.

Scoring apps aren't required to be encryption aware so they may not
be discovered and bound to when the PM is queried during bootup.
To fix this we perform discovery after ACTION_USER_UNLOCKED is seen.

BUG: 29073394
Change-Id: Ic423f3f06f42932724e5f7cc53ede3be1c4f2f13