Don't store invalid pkgs when migrating filters

Test: NotificationManagerServiceTest
Test: call method from test app, view policy xml file
Flag: none
Bug: 305926929
(cherry picked from commit bfa04e208995b05eee2a5336667f4e2dcd19fd30)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:85ccbd33e3766bbd22ced332cb5b9e983c2707db)
Merged-In: Ib7fcb733edd2cf2cbac0a7699763a5fe993b467e
Change-Id: Ib7fcb733edd2cf2cbac0a7699763a5fe993b467e
2 files changed