Just print warning log instead of triggering WTF

TrustManagerService.getUserId() not trigger WTF when receiving
broadcast USER_STARTED with userID = 0.

Bug: 155946337
Test: manual, flash AGO ENG image and then boot up
Change-Id: Id2ea54d8f4c25bd97b6213c431d18e44908d7e11
1 file changed