Fix Trust Agent discovery for FBE

Trust agent discovery happens earlier than unlocking the user's
key for file based encryption (FBE), so we need to explicitly
also ask for non-direct-boot-aware packages.

Additionally, never run trust agents for a user that hasn't been
unlocked yet.

Change-Id: Ice8a6510f163508abecfd83d627658f7aaa5107f
Fixes: 28537596