Check if Imsi encryption info are available

The original fix for b/74090333 (ag/3699759) was dropping all carrier
networks if carrier encryption info is not available. Instead, this CL
keeps the carrier network map regardless of encryption, and checks for
carrier encryption every time Carrier Network Notifier is being called.

Bug: 74090333
Test: Unit tests
Change-Id: I3f8b70c4a496053433a402008424638685ac8f71
4 files changed
tree: aa46b9e3a0e510d780f85e3c04613dab6257a5d0
  1. service/
  2. PREUPLOAD.cfg